my personal take away for it is say you invest 1k a month in stocks normally but you suspect that a drop is going to happen you have a few choices
1. if you believe it will be a massive drop (depression levels, massive bankruptcies and unemployment) then you should stop investing, take your profits from what you have and wait on it to bottom out before reinvesting.
2. if you think it will be a medium drop (something you can ride out without fear of your investments going bankrupt) then you can drop investment money to say 500 a month and bankroll that extra 500 a month to drop on the market when it does bottom out.
3. if you think it is a small drop then it will just be business as usual.
most of my personal investments are in things that will largely be unaffected by brexit so it is business as usual for me.