General advice -

1. A PCP is far easier to use than your pro sport, or at least easier to get good results with.
2. A charged PCP can sit for weeks or months at a time and be on target on the first shot, in general, it's not a problem
3. Once you have a cylinder and lead - around £120 second hand, then you will only need an occasional fill depending how much air you use (around £7/8), but we are talking many thousands of shots between fills for even a small cylinder like a 4/5L
4. You will get a decent gun/cylinder for around £600/700, cheapies are simply not as good, but it depends on your budget

If your unsure, put a help post up to meet up and have a go with one and have someone to run through the whole thing with you, I've done it for people in the pst, I'm sure there are shooters close to you who would help you out for a coffee

James