You know what? I have never seen this show. No reason. Just haven't.
I'd give it a shot. I think series 1 and 2 were probably the most inventive, and they tended to break the 4th wall quite a lot and explain to you the idea behind their con. It was an interesting twist on the idea. Series 4 was fairly horrible, but it picked up a bit in series 5.
They're currently repeating the edited for ads versions on Virgin 1, but I seem to remember you can't get freeview?