There's only a handful of Uni's that teach computer game development in the UK. You wouldn't be able to take themn without substantial computing background, so that's why you've had to go through the HNC+HND route.
I would say over the next couple of years, grab yourself a high-level development application like Blitz3D, BlitxMAX or Dark Basic for starters and write some little games. Start Small! Every newbie underestimates how hard it is to write a full application, and for their first game want to produce a MMORPG or FPS. Begin on primitive games like asteroids and frogger - that's how the whole industry started. This will introduce you to the logistics and actual experiences of writing code only to find it doesn't work and what it's like to spent half your time trying to find the bug. With these languages you'll find whether working out how to implement games works for you or not without having to worry about the complexities of the language. Only if you're happy with developing on those should you dive into C++ development with OpenGL and DirectX and learn how to create software through that (again, keep it small. You're doing this to learn the languages, not write a blockbuster. cover as many different genres and techniques as possible rather than committ years to one game). Then if you're still interested and aren't frustrated to death with computers and mind-numbing bugs, get in deep with things like creating a graphics engine. You're final career might not need that knowledge, but whatever you do you'll benefit from the understanding.
Things are also going to change quite a lot over the next 8 years, so by the time you've finished your course everything you learnt now might be obsolete! Multicore processing will be another thing you'll have to learn. Like many industries, you need to keep abreast of developments by following the media. The educational establishments on their own won't be enough to set you up.
Yo'll almost certainly need to be good at maths! Computers work in maths and you have to be happy breaking down problems into collections of number that you jiggle mathematically to get the results you want. I did A level Maths and Comp Sci and a lot of it goes over my head, and I need to constantly refer to books or webpages to explain things for me!
Um, there are different tiers of developer too. There's low level engine programmers and higher-level coders. You can get away with being less knowledgeable if you're not writing the engines and libraries that the rest of the team will be using. I don't know what the requirements there really are.
Finally, you need to love the job. There's no point doing this because it's something you'd like the look of. These days every man and his dog wants to either write computer games or work in computer graphics. In a lot of cases I think the dogs are better suited. I ended up doing Comp Sci and Biochem as a result of being encouraged into it by various sources, and at the end of the course I despised both. I would have peferred to study music but that option was closed to me because of choices made earlier in my life based solely on finances. If you're not sure this field is for you (and there is a world of difference between enjoying games and having great ideas for them, and actually writing games) I'd suggest you avoid it. What you absolutely must do is start coding for yourself. Build up experience. Build up demos that if you go ahead with this you can show to potential employers. Thankfully there's some really nice tools out there these days for starters to cut their teeth on, taking care of all the complexities and leaving you to learn the fundamentals of game design and implementation. Practice on those and you'll get a chance to see whether you actually like it or not, before commiting a substantial part of your life to a career path that, without actually trying now, might turn out to be a bad decisision for you! Take the 2 years course, which'll give you valuable experience (computer techs can be paid very well for a reasonable life depending where you land up, with less stress and woes of developers) and use that time to program and learn about yourself and what you're best suited to.
