Currency per language – always

Hi, is it possible to force a specific currency per language?
What I mean is, for example, if EUR is set for Germany and GBP for the UK, I’d like to prevent combinations such as EUR + UK.
This issue occurs when the wrong cookie is set (I’ve already enabled the Add query params option, but it can still happen — for instance, if someone first visits the GBP site and then clicks an EUR link).