Thanks for all the replies...
- yes have an electrical tester
- I did think about a more powerful model as this one does seem to get clogged up very quickly
At the moment I'm going to leave it for a while, we are just opening the window after showing, but mould is appearing on walls. We may get a quote from a cheap handyman we use who is an electrician for repainting, and doing the fan if it's reasonable may go with that.
In the meantime, the toilet flush broke yesterday so that can keep me busy with a DIY project :) The toilet keeps running water. Luckily have an isolator valve so have stopped it for mo, but will have to look at videos for that. Doesn't seem to be typical float valve that most videos show, nor typical dual flush - it is dual flush but has a cable to another part as opposed to pushing down on two parts. Looking forward to hopefully sorting it at weekend.
Thanks once again