Hi Sean,
My wife and I hit at least 4 or 5 a week down here in Dorset and Devon, they supply most of our 'stock' and have done for about 6 years now. We go less and less to auctions because of the high costs.
You will often find all sorts of smaller bargains but obviously not large machinery.
Thye best stuff (cheapest) seems to come from sellers with normal household stuff and kids toys, cltohes etc who have no idea what is in the box of rust on the ground at their table!
Recently we looked at a huge selection of very posh china and glass on a nice table cloth held down at the corners by 4 chunks of steel. The guy was gobsmacked when I asked if he would sell me the steel bits which he did for £4; got a really nice set of 4 chairmakers adjustable spindle rounders by SWAN which went back to the USA for £100+!
Your local paper will list local boot sales in your area, usually on a Friday.
Cheers, Martin