A lot of condensation inside windows

If there are no vents, how are the rooms ventilated? Was there any vents before the renovation?

I have single-glazed windows on the front of my house, and they turned into absolute waterfalls yesterday, as they do every time there's a cold snap - I do as the poster suggested above, soak up all the water with a microfibre cloth, and dry off with newspaper (bonus is that it's an unintended window clean!). I wouldn't expect it with double glazing tbh - I have double glazing on the back of the house, one set of patio doors in the same room as two of the dripping front windows, and none of those have so much as a drop of moisture on them.

Definitely consider if you're adding moisture to the air somehow, and maybe borrow or rent a dehumidifier to do a one-off drying out of the air, then try to avoid re-adding moisture after. But if it's in bedrooms, you'll never keep it dry, your breath alone will dump moisture all night long. See about re-activating the vents, it can't be a coincidence that the "sealed" rooms are the ones with condensation problems.

Bought a decent dehumidifier last week to help with this. It runs on auto during the night and there's no condensation in the morning. We pop it into the spare room to help drying the clothes now as well.

It'll probably depend on the size and layout of your house but I leave it in the bedroom through the night and move it to the landing during the day with all bedroom and bathroom doors open. If we're drying clothes inside I'll put it in the spare room with the clothes.

It is a bit of a pain moving it around but our bedroom in particular was really bad, blinds getting wet, curtains damp, and dark patches starting to appear in two corners of the room.