Hi Mat,
I've camped in Princetown, which I believe is with the area known as Dartmoor Forest. Generally speaking you can wild camp anywhere on Dartmoor as it's the only National Park where it's allowed (officially), there are a few exceptions and these are clearly marked on maps etc. These include military firing ranges (obviously!!) and farm enclosures etc. But as per normal, get there as the sun goes down and get up when the sun comes up, leave no trace and the world is good.
As for getting there, you're best bet is getting the train to Salisbury and then getting the train to Exeter, changing again and then getting another train to North Devon and getting off at Okehampton etc and getting a bus.
Or, if you planning a trip with a couple of others, find someone who could drive and share the petrol etc. When are you thinking of going?
Cheers
Mark
