Brighton Toy and Model Museum http://www.brightontoymuseum.co.uk/ is tucked away under the arches of Brighton Station. You can visit Arch One for free, where there is a shop, local information point and also a range of exhibits. It costs £4 for an adult ticket to the rest of the museum, children are £3 and children under 4 are free. Although it’s not a large museum in terms of floorspace, there is a huge amount crammed in, covering the walls and the ceilings.
I visited with my three year old in Spring 2012. The highlights for my train-obsessed son were two model railway layouts, one based on the Sussex countryside and one more industrial. There were chairs to stand on so that little ones could see, and one of them even had a button to press to start the train. I think that he could have stood there all day. He also loved looking through the display cabinets, which were packed with models of cars, buses, trucks and so on. There were some larger models too as well as toys, and lot of examples of various construction kits, including moving Meccano models. I liked seeing the farm and circus playsets, and there were a few girly toys too, with dolls and dolls house furniture.
It’s really easy to get to if you are visiting Brighton by train, and a short walk from the town centre and seafront. We were there for an hour or so, with an older child you could probably spend longer. Access to the main exhibition area is via steps, but you can leave a pushchair in the shop and because the museum is compact it’s not too far to walk around. I would really recommend a visit!