Just found this and a few things occur to me (I work with MPs):
How realistic are his chances of being elected (genuinely)? What is the incumbant's majority and is he fighting a safe seat or is it on his party's target seat list?
How far from London are you? Would he be living in Westminster during the week and then coming back to the constituency at weekends? Do you live in the constituency at the moment or do you plan to? I think some of these things make a real difference to the life MPs lead.
IME, MPs work incredibly hard, particularly when Parliament is sitting, but often also during recess. I would say that when Parliament sits they are often working from early morning (8am) until late at night. Every day. Particularly if they are at all ambitious and get involved with all the myriad things that MPs do (eg APPGs, select committees, various other committees such as Backbench business committee, 1922 committee, Public Bill committees etc etc etc). They are not "on holiday" during recesses. The main impact on family life is that most of them live away from their families from Monday morning til Thursday afternoon. This can be really hard. And then even when they are back home, they are still often very busy all Fridays and usually Saturdays (and sometimes Sundays too).
Do you work now? Would you work if he is elected? I think that can also make a big difference as essentially you are a single mother for a lot of the time. But if you don't work, you are just on his salary...
(BTW, a friend of a friend's DH is standing - Labour candidate, Wales, double-barrelled surname - if that's you, PM me!!).