I'm just glad the Speaker doesn't represent my constituency. The fact that a UK constituency is deprived of a choice of candidates is an anomaly that really ought to be addressed. Surely an elected Speaker ought not to continue being a constituency MP, so that a general election with a choice of candidates can take place in the normal way in his/her constituency.
In practice constituents have the same problem if their MP turns out to be the PM or one of the major minister; he or she is less likely to be available to do constituency surgeries and be available to listen to your thoughts.
I hate to quibble(!) but it's actually not the same at all. The main parties by tradition do not contest the Speaker's seat, so unless s/he is beaten by an independent or minor party, s/he gets elected by default. So any constituent who wanted to vote for one of the other main parties, is deprived of the opportunity to do so. The PM, on the other hand, has to campaign for their seat in the normal way. The PM and major ministers also have to ensure that they keep up their constituency duties if they want to keep their majority; whereas the Speaker, knowing that his/her seat will not be seriously contested, may feel less pressure to do so.