I've heard IRL and seen here lots of people planning to get the whole family tested just before the 25th in order to be able host/see elderly relatives.
But how would this work anyway? Like a friend was planning to go to Devon the day kids break up, isolate with nuclear family, get tested, then granny come to join them on the morning of the 25th. But how easy is to get a test in Devon? And doesn't it take a few days for the results to come?
And I suspect if I keep hearing this in people's plans, then lots of people are thinking the same. And I can't imagine there will be extra capacity at the testing centres on Christmas Eve. I've not had a standard issue test so I've no idea how easy/hard this is.