Well, my memory of our team game with me as Germany and you as UK with 3 TRN is that it was mostly you unloading two units (I guess in order to not waste transport space) into my deadzone in Eastern Europe, and four units per turn into Norway/Karelia, all of which I was also able to keep killing without much loss to my massive German stacks as they marched toward Russia. And your massive US force was busy in Africa somewhere, not sure where because they never really bothered me too much.
I seem to recall the Axis winning that one.
With 3 UK TRNs, I think the best play would be to just unload to Archangel where your units are safe, and I guess any extra money would go into fighters, or a Norway IC.
Also, offensively, tanks are much better value than fighters - half the price and they can actually hold territory, and they don’t suffer AA fire. Even assuming you could get ONE dozen fighters with UK, which I’ve never seen, it would still be better to buy TWO dozen tanks.
If UK came after Berlin with 3 Inf, 3 Arm and a dozen fighters, I’d wet myself with glee, because Berlin would be stacked with lots of cheap infantry and then some fighters and tanks for extra muscle. I’d dance with joy after the second round of combat when UK will have lost at least six to eight fighters in total to kill a handful of my infantry.