It all depends on how old you are. Go to your GP and tell them what you want to do, and your decision and reason behind that decision e.g. do not say that you cannot be bothered or you don't know why.
they will refer you to a specialist clinic. there is one that is nationwide that does all the abortions in the country mostly, unless you go privately.
As you are only 4 weeks pregnant, or round about then you should be able to take a pill, however over 6 weeks you need a proper termination as the foetus is half developed in terms of nervous system etc. by that age.
If you are under 18, or in full time education the abortion will be free
a word of warning however. from experience think very wisely about your choice, as getting rid of your unborn child is the most horrible experience of your life and will never leave your side
hope that helps xxx