There are many ways to learn German in the UK. Below you will find some useful links to start you off.
If you are currently enrolled at a UK university your first port of call should be the university's German / Modern Languages department and language centre. You can also check whether your institution has a DAAD Lektor, i.e. a DAAD-funded lecturer, who will be able to give advice locally.
Directory of DAAD Lektoren DAAD-funded lecturers at UK and Irish universities
Other useful links:
www.thinkgerman.org.uk/ Think German Campaign
www.goethe.de/ins/gb/lon/ Goethe Institute in London
new-cilt.org.uk/ CILT National Centre for Languages (England)
www.scilt.org.uk/ SCILT Scotland's National Centre for Languages
www.ucml.org.uk University Council of Modern Languages
http://www.aulc.org/members.html AULC Association of University Language Centres in the UK and Ireland
Online German resources:
www.bbc.co.uk/languages/german/ BBC languages site