hi-
i think the best way to handle this is to address it IMMEDIATELY. as in TODAY. delaying further will only add to your stress. i understand it is difficult to find the words but simply open your mouth and begin to speak. it will be fine.
i agree that november is far enough away that there will be no urgency for him to look. and it might also give him the impression it will blow over if he cools it.
if it was me, i think i would call him on the phone RIGHT NOW and say that you want to talk to him tonight about moving out. that will break the ice and take the pressure off of you immediately.
if it was me, i don't think i would even address the alcohol, as that might make him feel if he stops/lies/hides/manipulates that he can stay.
i would try something like this:
brother, we have decided that we would like all of our privacy as a couple in our home. we feel cramped and want to use our aparment for our grandchildren now. we have decided that it would be best for us as a couple if you moved out. we would like you to make steps immediately to find another place. we feel one month is enough time to rent a room somewhere else, so we have set a deadline of august 16th.
i would imagine he will try to persuade you otherwise. i would stick to my guns that you want to be alone with your partner, that you need some privacy.
he's using you and has stepped all over your boundaries.
you are not helping him by giving him a soft place to land. he's a grown man.
have you tried alanon or therapy? might be helpful to attend at this juncture, to receive assistance on enforcing your boundaries.
i would probably also do some research into his options. since he is a handyman, many apartment complexes will offer free rent to a resident handyman. or, if there is a university near you, there are often rooms for rent near the campus. there are always ads in the local papers for group housing.
good luck!