thanks for all your ideas and comments. We have had a trampoline with a net but is now needing replacing. I've found an oval one with a domed 'lid' to keep out leaves, Jumpking Pod I think it was. Still deciding. Agree they can be dangerous. Current TP model had levelling legs.
Back fence is now up, going to get path paved down to there but still unsure about floor covering. As dogs will use it as a loo :0( and the quantity of falling leaves we are swaying from wood chips to geocell, subbase and gravel. Obviously cost being a factor and not wanting to pave over oak tree roots and get the wrath of the Tree Preservation Officer!
Think we will clear the area of log piles and kids stuff and watch the drainage this winter before jumping in.
Have really appreciated all your opinions. Thanks again.