Well, I did two over the weekend and won't be doing another one in a hurry. It was an experience, mainly a boring one. Your advice came in very handy, thanks.
I got rid of about half the stuff and made £80 less about £20 for food and the pitch. The rest went to a charity shop yesterday.
Got there at 8:30 on saturday, there was about 30 cars there already so I arrived at 7:30 for the monday one to get a better pitch and there was only 10 cars there all day. Still sold a fair amount though.
I met some very odd people, people that won't pay 50p for a working radio but would pay £10 for a slide projector to 'watch freeview on'. Some folks appeared to be there from 7:30am until after lunch, wandering about.
It was just about worth it, the money means I have to buy one less boring thing for the new house.