dont think the public would care. a russian vaccine would be put through our trails and regulation, to show efficacy and safety before being used either way.
I'm not sure that would be the case. Rightly or wrongly, Russia is widely considered as one of the few countries to pose a significant threat to the UK's national security. It's also synonymous with dirty, underhand tricks. Whether you honestly believe Russia was behind events like the Salisbury poisonings, the death of Alexander Litvinenko, the sudden demise / illness of other opponents of the Russian government under suspicious circumstances and so on, they're not stories that evoke a sense of trust.
On a personal note, I think I'd be reluctant, though I partly have a distrust of Russian technology ever since I had the misfortune to fly on a Tupolev Tu-154 - never, ever again.
Aside from that there's the PR angle. For the west to be effectively bailed out by Russia; that would surely just be too humiliating. We'd be forever in their pocket, and I think it would have to be an absolute last resort for it to even be considered.
Here's hoping we don't need it - personally I have great confidence in the work being done by Oxford University. Fingers crossed.