Have you ever checked which services/packages are available in your area? If not, I will provide you a link to do it.
http://www.broadbandsuppliers.co.uk/...y-checker.html
Since you live in Brimingham, you can get Be broadband service which, in fact, offers high speed ADSL +2 broadband packages with speed up to 24 Mbps.
It is true that you may not achieve the speed that an ISP advertises. It is better to ask them to clarify you on this point. However, bear in mind that the distance between the cabinet/exchange and your premises is crucial for determining how much speed you will actually get.
You need to work out all this before you go for a high speed connection.
Good luck!