I like the challenger 2 move. Should pave the way for other countries to start supplying more advanced tanks like the Leopard 2 too, and although it's only 10 I'd kind of hope that they get used mainly for training and we follow them up with more so they can actually get significant numbers out on operations.
I hope we give them a lot more than 10. Maybe even 50%+ of the whole fleet. At the end of the day do we really need the tanks for anything else? Russia must be the main opponent we'd use the tanks against ourselves, so we might as well let the Ukrainians put then to good use. Let them do what they were designed to do!
We're highly unlikely to need to use the tanks in some expeditionary invasion or even defensive war not involving Russia, and even if we did the American Army would be providing the vast majority of the armour anyway.
Maybe we should just forget the Challenger 3 upgrades. If it really does meet our requirements the best then let's build some brand new Challengers from scratch to replace ones lost in / to Ukraine if we don't get them back. Otherwise we could consider buying some other model of tank (which Tbf is probably much more likely to be a good use of money than starting up a production line to build like 50 new tank bodies at the very most? Unless we rethink the number of tanks the army needs).
Logistics may well be a bit trickier, but Ukraine is used to supplying a very diverse range of equipment now, support systems can be put in place via Poland etc, and at the end of the day if actually using and supplying the tanks is more bother than it's worth then the Ukrainians don't actually have to use them (beyond a diplomatic tool to convince Germany to give them Leopard 2s etc), or they can just park them up in some defensive location near a border where they'll need minimal supplies.
I think we're past worrying about a few tanks causing 'escalation' too. Putin has escalated plenty himself, new tanks would simply be matching that. Any further atrocities / sabotage he has planned may or may not happen anyway, that's in his court - but he needs to know it won't make a difference to support for Ukraine.