I don't think anyone can answer your questions as we do not know the circumstances. Flying back to the UK should not be too complex, though bear in mind you'll need to fully isolate yourself for 2 weeks (including from the family) before you can proceed to do anything else. What I think would not be reasonable is to go with an expectation to easily return to the US soon afterwards. The uncertainty is high and you need to be prepared (but seem to be) to potentially stay in the UK for a long time if you decide to cross the Atlantic.

Many of us are facing similarly heart breaking decisions if it makes you feel any better. One always hopes to be able to resume some normalcy at some point, but the default assumption for now is that this may not be possible for quite a while and till it is, we may have to make hard choices in terms of our personal (and professional) lives that tie us for several weeks or months.