I'm glad that Labour has continued the commitment to supper Ukraine.
As others have said, Ukraine wouldn't be the end of Russian ambitions
There really are, unfortunately, parallels with the appeasement strategy of the 1930s.
The Baltic states have been explicit about the risk: that Russia's strategy is to take a little, re-group and then take more 
The West didn't react properly when Russia invaded Crimea. The consequence was that Russia was emboldened to continue into the rest of Ukraine. Putin has stated explicitly that he doesn't consider Ukraine to be a sovereign state. 
Ukraine is the only country in the world to have voluntarily given up its nuclear weapons, which was codified in the Budapest Memorandum of 1994. This guaranteed that its sovereignty would be protected. Russia, USA and the UK committed then to support Ukraine in the event of any aggression against Ukraine. 
Unfortunately, Russia proved that its commitments to international treaties are worthless. So why should anyone believe that it would respect a "peace treaty" that involves Ukraine giving up its sovereign territories? 
So no, I do think it's right that we are continuing to commit resources to Ukraine, for all our safety. If anything, we should be committing more and releasing Ukraine from constraints as to how or where they can use the assets that we send them.