Once you've mastered landings and have decent recovery reflexes, there's no reason why you can't fly where and when you like, except for public liability in the case where you hit someone/somthing or start a fire etc. If you're sensible about these issues, it shouldn't be a problem.

While I learnt with an instructor, I also played with the FMS simulator - it's free, and definitely helped me get going and meant I only had one or two flights with an instructor before doing my own thing.

Check it out:

http://n.ethz.ch/student/mmoeller/fms/index_e.html

Russell.