The UK government maintains a list all current Members of Parliament (MPs) and Lord’s.  These people are likely to be considered politically exposed, and should be included in any PEP screening that any organisation has if doing business in the UK. 

The list is publicly available (https://www.parliament.uk/mps-lords-and-offices/mps/) however most organisations will consume this data as part of a larger screening programme, which normally consumes this list, other sanctions list and Politically Exposed Person (PEP) lists to ensure that data is consumed in the most efficient method.