OP if it was unpainted do you have any pictures of that? And when were you given permission to repaint, with the agreement you would return it?
I think pictures and copies of messages will be key here. If I were you, I'd gather everything you have historically, then see how the check out goes. (But first make sure you take time stamped photos of the whole place the day you move out in lots of detail, especially any changes you made)
If they send you a message charging you for repainting, I'd reply detailing the reasons you don't think you should - not that you're pregnant and can't be bothered!
But - all changes were improvements
- when you first moved in, the house wasn't painted but only had undercoat (it would be great if you had an exchange to show they agreed this at the time)
- when you agreed to repaint it was X years ago, but maintenance has not been done on the property since then when you would have expected it to have been repainted in that time frame
Also, my memory is they can't just get an arbitrary sum, they need to provide receipts of work they've done.
We rented a house that was in terrible shape: landlord had been letting to students and wanted to switch to professionals without making any improvements. We were ok with it as it was cheap and short-term, got them to remove a load of broken down furniture they'd left there. Took extensive photos moving in (when it was so disgusting I had to hire a cleaning team of three because I could not face it). When we moved out I literally mopped us out of there, however it was a rainy muddy day and there were some footprints in the porch from where we collected the last suitcase which there was literally nothing we could do about.
They tried to suggest they were keeping 300 quid off the deposit for cleaning. I sent a calm (seething) email showing them my before and after photos, outlining in slightly official language why I thought they were full of it, and saying I was very happy to take it to the deposit scheme. They put all the money back in my account in a week. (Well, they notified the deposit scheme to release it). The main thing you need is evidence, if you'd been there longer I'd think differently, but honestly, its your HOME. You aren't borrowing a house. That's not legally how its viewed at all. You've paid above and beyond a mortgage interest repayment for more than just use of the house: landlords are required to do safety checks and a basic level of maintenance. They clearly didn't do the maintenance.
You may be unlucky, and it is possible they may try and get more money than the deposit out of you, but if you're buying Iwoudln't be so concerned about a reference and I think in reality they're not going to spend any money repainting, or at least not above what they should have spent over 9 years, even if it is twice as hard/expensive to paint over darker paints they should have painted twice in 9 years, particularly considering it wasn't properly painted in the first place.
I'd chance my arm OP, but I'd get all my documents ready.