Most computer courses use a surprising amount of maths, so definately focus on that, but unless you want to be a customer sales person or something like that, I don't think english is too much of a big thing. The most you'll use that for is writing up problem summaries of networks, or maybe a letter to some complaining so and so.
so basically, do maths.
You're obviously going to have to concentrate on computer stuffs too, e.g. different operating systems, hardware, software, networking. Get as much practice as you can.