A castle you can climb, a canal you can scoot, Ashridge for the weekend, and a high street with highchairs.
Berkhamsted makes family days out without a car if you live in the valley. The playgrounds are decent; the woods are the actual playground.
Buggy vs cobbles is a real High Street issue. The castle is free; Ashridge parking is not always.
Working swings, shade, fences from the road, and a bench for the adult who is pretending not to be tired.
Berkhamsted is small enough that an honest “best playgrounds” list should admit gaps. These are the nearest Dacorum options we would actually send you to.
Gadebridge is where the town holds Armed Forces Day, learns to ride a bike, and walks the dog into the water. Green Flag judged, civic by default, and the best free hour you can spend with children in central Hemel.