Thomas Paine observed that we would never have a “half-foreigner” President because of the natural born citizen clause.........
To be eligible to stand as an MP a person must be at least 18 years old and be a citizen of the UK, a Commonwealth nation, or Ireland. A person is not required to be registered to vote, nor are there any restrictions regarding where a candidate is resident.[6][7]
https://en.m.wikipedia.org/wiki/Member_of_Parliament_(United_Kingdom)#Eligibility
The only requirements to be Prime Minister are to be Member of Parliament and to be able to command the support of a majority of the House of Commons.
If you meet those requirements, the Queen is required to ask you to form a government.