Where can I apply for my student visa?

Heya please, I'm confused and need clarification from anyone who knows! I've got a psw visa till Nov 2011 but I've got an admission to study a masters degree in Jan 2012. Now I have about 45 days gap between my visa expiry and the commencement of my Uni. Can I apply from the UK or do I have to go and apply from Nigeria? Thank you