I've got a grip - I keep five years of receipts and payslips and stuff like that in it ...
If Bowland was dense forest x thousand years ago then it's unlikely there's megalithic remains. Same as the Wirral, same as Brum. Above that tree cover - roughly where the heather is now - there'll be loads of stuff. Little things. A person needs to spend a lot of time looking though. Is it worth it ?