qcamel - You seem to have the right attitude to all this.
My advice to you is: You have some sea awareness already and comfortable on water. Go and do the RYA Level 2 course, its only a few days, it will teach/refresh enough boating handling skills and rules of the road for you to cox your boat safely in fair conditions.
The RYA Level 1 is really an introduction to powerboating and does teach skills, but you repeat them in RYA Level 2. There really is no need to do this one. I target that at young kids or totally inexperienced people etc where it makes a great start for them.
Once you have RYA level 2, you should not be able to do and pass the Advanced course back to back, as it requires you to have experience. Any RYA instructor worth their salt will not recommend you do Advanced until you have a fair few hours in a variaty of conditions. Advanced extends your skills and confidence and include such things as night work, search techniques etc.
And so go play for a year and get your hours up at the helm. After that consider your Advanced Course.
Get a few books ... an Almanac from a chandlers, it will tell everything about your local regs, harbours, marinas, byelaws etc. Get a chart of your area and study it, take note of hazards etc and plan your routes onto a slate. This will help you on your early trips and having a good plan will reduce your risk of cocking up. Make sure the weather is good on your early trips to remove yet another set of potential problems. Watch your fuel like a hawk and think fuel & oil all the time. Work out how much you are using, this is vital knowledge for when you plan to go on longer distances. Fuel management is a key skill. Ensure you have safety kit and before you go out. And finally on your early trips keep your passengers down to a minimum, you don't need the hassle on your early trips, you must remain focused ... keep it all simple, there will be plenty of time later for all that, when you know the area and boat better.
Getting experience in your area is easy. Arrange to go for cruises on this forum with like minded people. They will not only give you local knowledge and help you learn.