Good morning Alan and welcome to the forum. Nearly, there, nearly a plot holder!!! When you say very overgrown, it it soft weeds or neck high brambles and nettles? What about water supply... it is nearby or half way across the site? Are you allowed fruit trees? Sheds? Polytunnels? How far from home is each site?
The site you looked at sounds friendly, which is a good start. Let us know how you get on, oh, and John has some useful articles on plot clearance in "Articles and Advice" at the top of the page, if you've not seen these already