Thanks for the suggestions
The children I'll have with me are all walking. There are lots of areas to literally fall off or over, as there is a large area of decking which has an edge all the way around the garden. The decking itself can be very slippy too. ( I hate decking!)
I like the idea of buckets and things for transporting, I know the little toy pushchair is popular for pushing about, so I might take out a shopping trolley & things to move around too. I'm not looking forward to it though!