Well in terms of meeting like minded folk, the madwalkers make lots of sense - they're the local ramblers group for youngish people. Nice people, decent walks, the odd weekend trip etc.
You're brilliantly placed for hiking in Manchester of course - several bits of the Peak District in no time at all, Snowdonia is fine by car and just about possible by train, the Lakes easy by car or train and the Yorkshire Dales/North Pennines fairly plausible too.
And thats just the obvious spots
The Lakes are probably the most obvious area for wild camping. Trains round to Windermere or round the coast.