On our own (U.K.) we are vulnerable to an attack. But we would not be a push over. However, as part of NATO, there is no way that Putin would mount any kind of serious attack against us.
That goes for many other individual NATO member countries.
The whole reason according to those who agree with Russia’s position on this situation, is because Putin is afraid of NATO. Even though NATO has never threatened Russia.
So we (U.K.) and some of the other members of NATO (but not actually NATO itself) should be taking advantage of Putin’s fear of us (and NATO), by assisting Ukraine in defending itself by providing military assistance. And making sure that we tell Putin loud and clear that we WILL be doing so.
Why else would he make so much effort to tell us to stay out of it?
If we continue to sit on the sidelines, Putin will see that as a win for him, even if the war he has started does not go as well as he expected.
Is that really what we want?
And if Ukraine (in part, or in whole) falls, the situation will be even worse. Putin having seen us just watch, may build up his military again and then at some point in the future, do the same thing again.
And we really don’t want that to happen.