In reply to mc2006:
Clubs vary. Some are brilliant, most are pretty good, some (sadly) are cliquey. Ultimately, as in anything, either people will be keen to help you or they won't. If the latter, don't waste time - find another club! Most of the time though, people will be really helpful. We all had to learn from others and everybody in climbing knows that. So they know (or should know) to pay back. But, simplistically, in climbing, you'll tend to encounter pretty altruistic people and pretty selfish ones. Stick to the former!
Re indoor climbing, sure, depends on the wall but many walls have steep, juggy 5s, which are ridiculously pumpy. You almost never get climbing like that in the UK! So, while they're good for fitness, don't worry too much about them. More easily angled 5s, which require good footwork, will be far more valuable for you right now.
I would start leading (indoors) as soon as possible. If 4s are OK, are there any 3s you could lead? Or, if you've top-roped a 4 OK, could you then lead it? And could you have a go at 4s that you haven't top-roped? (Depends on how you're feeling.) It's just that leading is such a fundamental skill - working out what you're doing, clipping, resting, reading the plastic/rock, committing to a move. And the sooner you begin, the better. Leading on a climbing wall is pretty much as safe as it gets - but, if you're nervous, why not ask a staff member if they'd mind watching you just for a couple of minutes to make sure you/your belayer's doing everything OK?
The important thing to remember is that every last one of us has been where you are now! And the good thing is that a world of delight awaits you. You just have to enter it... safely.
Mick