No, I would fight and that would be fine, it is fine for people in Ukraine to fight for their country. For the rest of the world we should limit our assistance to one which doesn't make us the military industry of Ukraine because that risks escalating to a level that simply is not worth it. Similarly I may take a loss on losing my wallet to someone with a knife to my throat rather than fight him to the death over a £20 note.
If anything not supplying weapons could increase the chance of prolonging the conflict (and all the potential tail risk that goes with that), make things worse for the humanitarian disaster already taking place, lead to more massacres etc.
Zelensky can't just act unilaterally in any peace negotiations, he's bound by Ukraine law/the Ukrainian constitution - he's made that clear publicly too and I guess the penny is dropping for Western leaders, some of what might be on the table in any peace negotiation is going to be subject to votes in the Ukrainian parliament and potentially a referendum. Russia is clearly trying to take a chunk of the East right now but should they be successful in doing that that presents a bigger risk for prolonging the conflict as the stronger Russia's hand in any negotiation the lower the odds that Zelensky can actually achieve a peace deal that would be palatable to the Ukrainian population.
That's why it's pretty critical for the West to ramp up support now, they really need to make sure Russia doesn't cut off a huge chunk of the Ukrainian army in the East, if Ukraine can prevent the current attempt at encirclement and (hopefully, once they've got it to the front lines in a couple of weeks) smash the Russian forces with all this new artillery and armour they've been delivered then we could end up with more of what we saw north of Kyiv, Russia having to withdraw from the East, their negotiating position diminished and a much better chance at a peace deal that can be approved within Ukraine.
Zelensky ideally wants to get back the land taken pre-full invasion in the East and potentially Crimea via a future referendum on the issue, if they're in the position where instead Russia is holding or has annexed an even bigger chunk of the east + south then they're facing Russian demands not just for them to give up the land previously taken but to also agree to give up even more... even if Zelensky wanted to I doubt he'd be able to sell that domestically, that means a longer conflict dragging on.
We can't stop the Baltics or Slovakia or Poland from supplying arms, they're NATO members too, the risk is already there, it's probably better overall for the UK, even from a purely selfish position, to supply Ukraine with weapons and maximise the effectiveness of their military efforts right now as that's the quickest way this thing ends and all the possible tail risk scenarios from this thing escalating or spreading dampen down a bit.