The dinosaurs in the main hall of the Natural History Museum stop children mid-stride. That is where this tour starts, because it is the best illustration of the whole idea: entry tickets, parking, lunch, ice creams and the gift shop on the way out add to the cost of a family day out, but national museums in London, Edinburgh, Glasgow, Cardiff and Belfast charge no entry fee, and parks and beaches are open to everyone. The journey below runs south to north — London, then open country, then Scotland, Wales, and Northern Ireland — and the biggest cost on any of these days is usually food, which is why the picnic matters as much as the destination.
London: dinosaurs, science, and the Rosetta Stone
London's free museums include several suited to families, and South Kensington is the place to start. The Natural History Museum in South Kensington is the classic choice: dinosaurs in the main hall, the blue whale skeleton, and galleries on volcanoes, earthquakes, and human evolution. It is free to enter, though it gets busy — arriving early or booking a free timed-entry ticket online in advance makes the day much smoother, and the first hour after opening is the quietest time at the most popular free attractions.
Next door, the Science Museum offers hands-on galleries, the Wonderlab (which does charge), and the ever-popular space and transport sections. A short walk away, the Victoria and Albert Museum has family trails, a beautiful courtyard, and galleries that appeal to older children interested in design, fashion, and jewellery. A packed lunch, snacks, and water bottles turn a free day into a genuinely cheap one, and the museum courtyard is a natural place to eat it.
The British Museum in Bloomsbury is another free giant: Egyptian mummies, the Rosetta Stone, and galleries spanning the whole of human history. With younger children, pick one or two galleries rather than trying to see everything — the museum is enormous, and a focused visit beats an exhausting one. Many free museums run free family activities, trails, and workshops, especially in school holidays, so a quick look at the museum's website before you go can turn a good day into a great one. Let children choose what interests them, and pick a focus of two or three galleries, not all of them.
Open country: parks, trails, and beaches
Leave the museums behind and the free days out get wilder. Hyde Park and Kensington Gardens in London offer the Diana Memorial Playground, the Serpentine, and miles of paths and open grass. Richmond Park, further out, has wild deer, ancient trees, and views across the city — a genuine countryside day out inside the capital, and a picnic on the grass costs nothing at all.
Outside London, the Peak District National Park has free-to-walk trails for every level, from gentle family strolls around Chatsworth's parkland (the house itself charges) to the stepping stones at Dovedale. The Lake District offers lake-shore walks, woodland trails, and stone circles, all free to explore, with the cost limited to parking and an ice cream. For a coastal day, the beaches of Cornwall, Devon, Northumberland, and the Welsh coast are free to visit and offer rock-pooling, sandcastles, and coastal walks. The South West Coast Path has stretches suitable for families, with cafes and pubs along the way for a rest stop. Arrive early here too: car parks at the most popular beaches and trailheads fill first, and an early start buys a quieter walk.
Scotland: Edinburgh's volcano and Glasgow's Spitfire
The National Museum of Scotland on Chambers Street is free, with galleries on science, nature, world cultures, and Scottish history — plus a rooftop terrace with views over the city. The Royal Botanic Garden Edinburgh is also free, with glasshouses and family trails (some exhibitions may charge). Arthur's Seat, the extinct volcano in Holyrood Park, offers a free, leg-stretching climb with panoramic views — best for older children and confident walkers, and worth saving for a clear day when the view repays the climb.
West in Glasgow, Kelvingrove Art Gallery and Museum is free, with everything from a Spitfire hanging from the ceiling to stuffed animals, suits of armour, and a much-loved organ recital. The Riverside Museum, Glasgow's transport museum, is also free and a firm favourite with children who love trains, trams, and tall ships. Booking ahead where possible applies here as well: several free museums offer free timed-entry booking online, and booking avoids queues and guarantees entry on busy days.
Wales: Cardiff's museums and an open-air village
In Wales, the National Museum Cardiff is free, with natural history, art, and geology galleries. St Fagans National Museum of History, just outside Cardiff, is an open-air museum of historic Welsh buildings set in parkland — also free — where children can walk through centuries of Welsh life, from a medieval church to a wartime prefab house. St Fagans rewards the picnic rule more than anywhere on this tour: parkland, buildings to wander between, and a whole afternoon that costs nothing once you arrive.
The Welsh coast belongs in the same day's thinking. Beaches along the Welsh coast are free to visit, and a coastal walk followed by a picnic is the cheapest version of a seaside day anywhere in the UK. Check for family trails and events before you go — many free museums run them in school holidays, and a trail turns a walk through old buildings into a hunt children actually want to finish.
Northern Ireland: basalt columns and a Belfast garden
Northern Ireland's Causeway Coast offers one of the UK's most dramatic free days out. The Giant's Causeway itself — the famous basalt columns — is free to walk, with the visitor centre charging for parking and exhibitions. The clifftop walk from the Causeway to Dunseverick Castle is free, windswept, and unforgettable. Bring layers: a windswept clifftop in any season is colder than the car park suggested, and a picnic eaten out of the wind tastes better than one eaten in it.
In Belfast, the Ulster Museum in the Botanic Gardens is free, with galleries on art, history, and nature, and the surrounding gardens are a pleasant place for a picnic. The Titanic Quarter's outdoor spaces and the slipways where the great ship was built are free to walk around, though the Titanic Belfast exhibition itself is ticketed. That distinction — free to walk, ticketed to enter — runs through this whole tour, and it is worth checking before you promise children the exhibition rather than the slipways.
One thing to do tonight
Pick one stop from this tour and book its free timed-entry ticket tonight, if it offers one — the Natural History Museum is the obvious first choice — and pack the picnic while you are at it. That single booking, made before the weekend, is what turns a free day out from a good intention into a day that actually happens.