Pred...BBC Bitesize is your friend if you need to brush up on the long division/mulitplication. Have a look at how to multiply/divide with decimals as well. I spent about a week setting myself questions on paper and trying to answer them as fast as possible. A cliché I know but..
Fail to prepare...Prepare to fail!
http://www.bbc.co.uk/schools/gcsebitesize/maths/number/