Dear Ben,
Thanks for your email. I will try to help you as much as I can. There are many ways of improving english, but I'll tell you just few, as you don't have much time.

Firstly, the most you can improve your english just by communicating with person whose native language is english. That'd halp a lot. You'd learn common phrases and words. However, even if it helps you in pronouncing words and communicating, it won't help with writing.

Secondly, it is very important to read englsh books. But if you don't have time for books, you could read magazines. They're helpful too. Magazines help more at writing that pronunciation. It is more different language than talking to one person.

Thirdly, another good way of improving your english are movies. When you don't have much time, you can watch a movie in english, without subtitles in your language or in english subtitles - that way you can both listen and read, and if you don't understand something, you can learn from the happening actions in the movie.

These are very different ways, but I hope you'll use some of them. I hope I helped.