Discovery Centre, Museum of Gloucester

The Museum of Gloucester's Discovery Centre sits right in the heart of the city, and it's the sort of place that rewards a proper ramble around rather than a quick zip-through. You get genuine hands-on stuff here - actual objects from Gloucester's past that you can handle and examine, which beats staring at things behind glass any day. The Roman section is genuinely good, given that Gloucester was a proper military stronghold back then. Kids actually engage with it rather than dragging their feet, though I'd say two hours is about the realistic limit before boredom sets in. Free admission is the cherry on top, which makes it an easy call when the weather's being difficult. It only opens Thursday to Sunday, mind you, so plan around that. The city centre location means you can couple it with a walk along the docks afterwards - Gloucester's riverside is worth your time. If you're camping at The Glamping Orchard just down the road, it's a brilliant rainy-day option that won't eat into your holiday budget. History types will find plenty to sink their teeth into, though it's not so overwhelming that families with younger children feel lost. The staff know their stuff and aren't the stuffy sort, which genuinely makes a difference.