Preferable you need 5 GCSE's, including maths and English grades 4-5 ( C-C+/B-). Depends how many you did and what you got in Maths and English really man. Some elite Universities look at GCSE grades alongside A levels/L3 BTEC Equivalents, but most don't. Hope this helps your answer. I stayed on 4 years at sixth form and got 4 A levels, 2 BTEC L3 Sub diploma equivalents and finally passed maths grade 4 in my final year.