I think sending troops from NATO countries to Ukraine will be seen by Russia as a intervention from NATO, and is a bad idea, 2nd thought on this is that the UK army is already suffering from low personnel, low morale and under equipped, not to mention veterals being abandoned.
We need to sort our own Armed forces out first, make it something people want to join (regardless of their ethnic group, gender or other things) and build something that can be deployed quickly to multiple theatres, and allow for regular rotation.
We have ex soldiers homeless on the streets, WHY!!?? when many have put their lives on hold to serve this country, they should be looked after properly.