My boiler has been fixed. Flat is toasty and I had a proper shower this morning.
The cold forced me to keep active; that and the extra time I spent at home, waiting for engineers and inspectors, enabled me finally to restore the flat to a level of tidiness it hasn't seen since my ex departed these shores. She was a packrat to the extent that the narrow hallway had three large recyclable shopping bags just full of other shopping bags; the walls became noticeably closer together and all free space disappeared under her tide of useless clutter. My workload has meant I've only been able to reclaim the flat slowly, one area at a time. Finally (and with the aid of a steam cleaner), I can happily leave any door in the flat open when other people are visiting. This removes a depressing influence from my environment in a way that would be a mystery to my ex, for whom the clutter was obviously a defense mechanism.