Welcome to BPNet Ed, glad you've joined us! It's great that you are taking this time to do your research and set up a proper enclosure before you purchase your first ball python. That kind of prep work will surely pay off for you and for your snake.

As far as age, really it's up to you and will likely be determined by the individual snake you simply fall in love with and must have. We've had babies that were lovely and adopted adults that were just as nice to handle and also others that took a fair bit of patience and work to settle them down. The best thing is to learn what to expect from a breeder (much better than buying from a pet shop), what to look for in a healthy BP...that sort of thing. The purchase process can really be very important as no matter all the planning and prep if you purchase a sickly, non-eating BP of any age, your first experience isn't going to be easy or much fun.

We have a number of members from England (some that breed BP's) that may be able to be a great resource for you on BP breeders, suppliers of caging needs and feeder prey, as well as herp groups near you.