I would say early mines could be the solution. Brits are the only faction that can't build an early sweeper, yet they extensively use light vehicles in the early game.
The UC is really early, firstly trying to lay a mine in a frontline spot that early is going to get spotted (probably by the uc which then kills he pios while they lay it) and if you spend 50 on a teller you don’t have the Faust when the uc overextends.
The big problem with fighting a uc is you can’t extend, you have to huddle in cover with you units close to support to push it away.