Thanks to everyone for their input, I have now decided to do the
following,
1. Buy a shredder to deal with the greenery and smaller branches
2. Create a habitat pile with the heavier un shredable branches and
burn them in a small open brazier on an as and when basis.
3. Use the trunks for some form of garden construction, ie as edging
for a border or a low raised bed.
4. Keep a few of the trees minus their foliage but still in the ground
as hammock slinging points!

Thanks again for the very useful and constructive advice.

John