Certain post-holders are disqualified from becoming a Member of Parliament. These include:1
civil servants
members of police forces
members of the armed forces
government-nominated directors of commercial companies
judges
members of the legislature of any country or territory outside the Commonwealth
peers who sit and can vote in the House of Lords
bishops of the Church of England (known as the Lords Spiritual) who are entitled to sit and vote in the House of Lords
This list is not comprehensive and detailed lists of disqualifying offices are set out in the House of Commons Disqualification Act 1975 (as amended).
Other office holders standing at a UK Parliamentary election
Members of Senedd standing at the UK Parliamentary election
Whilst Members of the Senedd can stand as candidates in a UK Parliamentary election, they cannot be Members of the House of Commons. If successful an MS would have to resign their seat in the Senedd within eight calendar days of being elected to the House of Commons.2
Members of the Scottish Parliament
Whilst Members of the Scottish Parliament can stand as candidates in a UK Parliamentary election, they cannot be Members of the House of Commons. If successful, they would have to resign their post within 49 calendar days of being elected / taking the oath of allegiance (or making the corresponding affirmation).