www.afors.co.uk
www.thehangar.co.uk
www.ukga.com
All carry a good selection of such adverts (actually, they very often carry the same adverts!)
Incidentally, and on a related subject, does anybody know of any interesting FW shares going at Denham?, I'm moving over that way, none of the normal sources have anything and I haven't managed to get over there for a gander at noticeboards yet.
G