Im going a similar route as I have almost done my 2 year course at college and I might be in the same state of mind as you since when I went to the university for preview day, I could feel 2 things, excitement and being really sure that I might actually struggle in the academic lifestyle you just mentioned. I didn't do well in the academic route, I haven't actually got any experience like you have so I don't know how my BTEC level 3 course balances against your 'various qualifications'. So in a sense I probably left the academic path at the same time as you did but instead you took different things like Microsoft Certificates.
Nevertheless I am going to take my university course seriously and do the best that I can, i've not really been one for doing well in the academic pathway but I am going to dedicate my time to achieving top grades, sure there will be times where I can't deal with the stress of so much work I have to do but these times are when I will just deal with it no matter how hard it is - that's how I jumped from being a lazy guy with crap qualifications to working hard and dealing with large amounts of work.
As some advice (This is if you are set on the web technology pathway) if you were to take a college course for 2 years, well I don't know any course centered on web technologies but IT i think is closely related, there are a few units that involve web development and its a really good course and i've learnt alot. You don't have to follow my advice