Where Can I Register/Write GCSE A Level Exams For Entry Into UK Universities?

Please i wish to apply for entrance into a uk university next year.
I applied this year via UCAS with my waec as my highest qualification. I was rejected by 4 of the universities based on insufficient qualification and was accepted by only London met which i hear is not a good university. I had to defer my admission till 2010
Now i wish to broaden my chances of admission next year by writing the gcse a level exams (Not the WAEC own please) I have no idea of the structure of the exams, where to register or when the exams are coming up.
Please anyone with idea should help me, i beg. Thanks