I think the lack of a self destruct ability for the glider is fine. You're paying a decent amount for a forward hq, and it gives many advantages, but similarly you should be punished for being reckless with how you position it. This goes for OKW trucks and Soviet forward hq too, which are investments you make based on how well you think you can hold a territory, and if you fail to, you lose them fairly. This isn't the same for USF because they're a faction designed to be mobile but fragile.
As for your suggestion about the UC, it's an interesting one, and personally it would be more intuitive than what Brits currently have. However, as Brits are atm, the UC does not need a mortar given how fiendish the mortar pit is. Axis setup teams are punished enough by this thing, and as a static faction, Brits don't need such a mobile option considering the UC already has WASP (debatable as to how effective, but still an option).
Tbh, Brits need some changes to their main gameplay before things like UC get a rehaul.
