What is wrong with my lights?

I’m having trouble with my downstairs lights basically…and wondering if anyone can help before I call my landlord (yeah I know I’ve asked another question about something that’s wrong with my house…but I’m trying to be all independent woman capable of DIY etc.!)

When I press the switch in either the living room or kitchen the lights momentarily flicker and don’t come on. If I try turning the switch on and off they don’t even flicker after that. If I leave the switch on the lights seems to come on a few hours later…sometimes… sometimes they don’t.

I’m not on a payment meter and the fuse is fine in the fuse box….i.e. it’s ON. I have recently had a leaky roof near the front door, but have been fixed now…but worried obviously that there maybe water in the house cavities or something…could this be causing the problem?? I don’t know…any help would be great! xxx