Good news - Mum's almost certainly NOT dying imminently.

The shadow on her brain is, according to the specialists, almost certainly a 'central neurocytoma' - which is almost always benign (thus unlikely to spread) and has an approx 80% cure rate with surgery. Assuming that goes well, her life expectancy will be the same as any other healthy persons' of her age.

She did still have the fall, and that was likely due to an infection she picked up as a result of not quite being able to look after herself properly any more. Being the stubborn old Brit that she is, of course, she refutes all claims to that effect, but it's clear she does still need (and will need more of, as time goes on) more care/company, so  mightymightyena and myself are still going to move over there to take care of her; the difference now being we don't need to be packing our shit and jumping on the next plane available. The hospital is already processing arrangements for home care for her, and she has her friend a few houses down and the dog walker (who's also been an angel during all this, taking extra time caring for/spending time with Mum's dog at no charge while she's in the hospital) so she'll be okay until we get there.

Now excuse me while I process a several-week-long sigh of relief.