Hi Nick
You should have posted this under The Bothy. It is more active.
It's a bit late for a reply now, but I think most National Trails lend themselves to wild camping provided you stay away from habitations, camp late and leave early, and leave no trace other than a bit of flattened grass. I’ve wild camped the South Downs Way, the Pennine Way (both excellent for wild camping); the Cotswold Way, and the Thames Path (camping gets difficult inside the M25). All are accessible via trains and/or buses at the ends and some intermediate points.
Elton

Hi,
I have managed to bargain 4 days of hiking in July :).
I'm trying to pin down some options given:
i) I want to wild camp
ii) it is UK and ideally accessible reasonably without a car
iii) i do not want to endure midge misery

apart from that anything goes!
Anyone with some ideas or experience would be wonderful.
All the best,
Nick