Steps to separating from partner

So I've been thinking about leaving my partner for a long time but haven't of course because I don't want to uproot my kids and he won't leave, so I realize I will probably have to do it. We have two houses. One is being used as a short term rental property and I'd really like to move back there but we are planning to do a renovation on that house late next year so my plan was to leave him and move there once the house is finished, but I can't stand him sometimes man. I just want to separate but at the same time I know it's prob smarter to just wait until the house is done. What would u do? How did u leave or are planning on leaving?