I am a British citezen , but I have been living abroad for 5 years and I finished high school in another country ,so what do I have to do to study in london ?

I don't understand your confusion - you apply for admission, same as everyone else.

Or am I missing something?

I live in kosovo I am not sure if you know where kosovo is... anyway , I want to know what do I have to do to study in london ? I'm sorry if I am being confusing

You have completely missed admission for the next intake and either way you would need outstanding grades in your chosen subject.

UCAS - Home (http://www.ucas.ac.uk/) are the people that deal with all UK university admissions.

So there's no chance for me to study in london , because my grades are not outstanding

This intake year is certainly out.
There are about TWICE as many students chasing places then there are actual places this year, so the universities can chose only the very best ones.

I'm interested in studying architecture , what about aplying next year ?

You can try, but, as I said earlier, unless you have OUTSTANDING grades you don't have a chance.

Thank you verry much I needed this info , but what van a guy like me do ? Just give up on uni

Honestly, yes.
That isn't the end though as you could try getting a job with an architect firm and go from there.
Some offer "on the job" training.

thanks again sorry for the trouble =[

If you're native English, there are no issues to apply for an admission at London University.

For a British Citizen, there are no issues to get admitted in a London Based University. In your case, as your grades are very low, you'll have to improve them first. Coming session is Spring (January-February) and surely you would not be able to improve your grades during such a short time span. I would suggest you to improve your grades first and consider Fall Intake (September 2011).