well i bought a Bounty hunter Tracker IV about 5 days ago and i am having trouble finding any coins
and today i went to Delemer forest about 20 mile from where i lived i got there spent £4 on parking and within 5 mins of me starting to detect he turns around and goes "you can't detect here even though its public land" and i was so annoyed at that but told him sorry and left
Yep, even public land owned by councils etc. has bylaws, so you do have to be very careful. Every bit of land in the country belongs to someone, so you will always need permission in one form or another. Try knocking on some farmers doors, you are in a pretty good area for getting permission to detect, the northerners have a much easier time of finding land to detect on than we southerners.
Beaches are a pretty safe bet, you can get your Crown Estate metal detecting Permit here and see also the Crown Estate Metal Detecting Permit Terms and Conditions.
I put a link to a club in the other thread you posted, that would be a great place to start!