Your best bet is to get an accountant who can explain everything to you. I was in a similar state, worrying about what taxes I had to pay and when, and my accountant explained it all to me in a very easy to follow fashion… and how to be the most 'tax efficient'.

The best thing he said to me was, "You go out and concentrate on earning some money, and I'll tell you what to do, and when. Don't worry about it, I'll take care of it." 

I'm set up on QuickBooks to sort out my invoicing etc.