�250 isn't a huge amount in investing terms, but that shouldn't put you off investing wisely. I would recommend you placed it in a standard savings account. You can get some good deals (certainly through online savings where they can save a little on overheads) and you can get some ok returns. If you are likely to contribute (even a small amount each month) regularly, look for an account that pays regular interest, for example monthly. If you then accrue a large amount, and wish to play the money markets, consult a financial advisor, but make your own decisions, don't be pursuaded!
Hope this is useful.