How can I improve my english as much as I can for the next 3 months.?

Hello guys, I've been living in london for the past 4 years. I still haven't got the hang of the english language though. I got an offer to get into an english uni to do Aero engineering. I'm scared now because my english is pretty crap and I will be living by myself at the uni. I only have friends from my homecountry, no english friends so far. :( I think I'm pretty screwed. I wanna improve it as much as possible till september so that I won't be left out with my uni friends :(. Please guys help me.