Hey guys!

I'm considering beating the main quest, but don't have some of the annoying side/radiant quests done. Assuming I don't destroy the factions I have yet to complete quests for, will I still be able to complete them after the main quest? And if not, around which quest do they become inaccessible?

Thanks!

Most you can still do but fallout.wikia.com has a lot of stuff about stuff like that but beware of spoilers

Yes, you can still do side quests and radiant quests after completing the main quest.

except MM radiants quests are turned off completely after the patch, I only get the misc settlement attacks since then

Yes, but you will loose quests from whichever factions you alienate.