You can take CLEP modules and take exam here in UK
About the College Level Examination Program (CLEP)
I know there is a CLEP exam centre in London, here are the company's details:
TrainE
314 Regents Park Road
London,
N3 2JX
0044-208-371-3280
I made contact with a guy there, who informed me that they hold CLEP exams twice a week.
Not sure of any other centres in the UK.
Hope that helps,
Pad