Not exactly UK, but in this global times the USA arent far away ;0)
I have been renting a webspace from Topclasshost.net for almost 5 years now. They are reliable and good. Only bad thing about them is that IF some problem happens it takes its time for them to solve it... but worst case was a server that did burn out - and that was replaced in just 2 days with backups almost from the moment of the server's death.