This is a very interesting yet a very common question. Most people think changing names is a big hassle. Well I think it is relatively easy to change your surname in UK. The first thing you need to do is that you need to prove your identity by giving in copies of your passport, driving license etc. These documents would be used to provide your proof of identity, to prove your address you would be required to submit a bank statement and two utility bills. Once you have these documents there are two different ways to change your surname. First is by either by Deed Poll or Statutory Declaration, both these procedures are legally accepted in the UK.
When all the documents are in order, these need to be witnessed in the presence of a lawyer or a commissioner. Once your name is legally changed, it is considered as a legal offence if you use your previous name in any case. It is best to get more than five copies of the original certified document. This is because at times government bodies require submission of original documents. So it's best that you have spare copies available at hand.
Hope this has answered your question to some extent.
When all the documents are in order, these need to be witnessed in the presence of a lawyer or a commissioner. Once your name is legally changed, it is considered as a legal offence if you use your previous name in any case. It is best to get more than five copies of the original certified document. This is because at times government bodies require submission of original documents. So it's best that you have spare copies available at hand.
Hope this has answered your question to some extent.