As I'm still new to the area I now live in, I thought I'd have a game of Left - Right this afternoon. Left out of my house then 1st Right, next Left, next Right etc to see where I ended up. The answer was Chepstow, via a few lanes I'd never been along before. The rules are simple, just ignore any road that is marked No Entry or No Through Road and if you do end up in a cul de sac, just come back out and pretend it never happened. It can get a bit tricky in town, you can end up riding miles around housing estates or you can just choose roads that are signposted to somewhere until you get out into the countryside again.
Have a go, you might be suprised where it takes you.