Do your A-levels if you can stomach an extra year of school, then if you fancy going to uni, do a business degree or something other than computing.
Computing degrees don't really seem to help a great deal in terms of career prospects. If you get a business degree, you'll have a greater understanding of business processes and operation. This will be of great use to both yourself and your prospective employers, whether they employ you as a programmer, systems analyst, or project manager.
Otherwise you'll end up being stuck in some tech support role for god knows how long.
If I was to start again in life, I'd do something other than IT. While they pay can be good in some fields of IT, in others it is not commensurate with the level of skill, knowledge and education required to perform the job. Added to this, the market is saturated with lots of tech savvy young people looking for jobs.
You should try and find a niche profession and stick with it.