Wow, your story is very familiar to me (without the successful startup, sadly!). I'm British too, and simply found all the options available to someone interested in the web severely lacking. I'd done a couple of years of building websites for small businesses and such, and I was pretty much ahead of everyone I could find (admittedly I was from a fairly sleepy area).

I ended up joining a course but dropped out after less than a month; the first sign that it wasn't going to work out was at the initial interview where someone said "You've done some web work I see? I bet you'll be able to teach me a thing or two!" that person was the head lecturer.

Algorithms, advanced maths, and cryptography are also the areas I feel I lack.

All in all, I don't think I've suffered in the slightest either. Finding the first job was probably a bit tricker, but in hindsight I've had an additional 3/4 years earning good wages than those people who did do the degrees. I'm not strongly opinionated as to whether they're worthwhile or not, but I don't believe I've been negatively impacted by it.

I have thought a few times that the traditional style of education simply isn't applicable to some people; I was never very good at school, but flourished once I learnt how to teach myself what I wanted to learn.