Toilet is fixed. After getting declined by two plumbers, I sent out another request, and this time May Day responded. They're also based in Folkestone, they said they could fit me in today, and he came and fixed it at lunchtime. He didn't use the replacement flush I bought, said he could get a repair kit locally, so basically just replaced the perished valve. He told me how and where to get this too so I could fix the other two toilets myself, nice.
I have not seen the bill yet, it might be outrageous. Hopefully not.
Thing one had his vaccine today.
Coronavirus weekly death graph for USA + Brazil + India + Mexico + Russia