The teachers have checked out whether it is possible to hire me (and it seems it is) but it limits my ability to earn and function in the system. Hence the need for a course.
In this case, the best bet is to look for a course (a lot of them are EU funded and free) where they'll turn a blind eye to your limited Polish schools. A lot of it is 'by negotiation' - it's just a matter of finding someone to agree. A lot of the standalone courses are provided by people that couldn't care less as long as they get the money, so it's not that difficult to pull off.
but I was told both these points were totally irrelevant!
Hmm, a lot depends on how they've previously been taught. If they've had native speakers since 6-7, it's a doddle to teach older kids. But if this is their first contact with a native speaker, it can be rough going, as they simply won't be used to being spoken to constantly in English as most Polish teachers will instinctively fall back into using Polish.
I used to (before changing career : got offered a job with a salary that I couldn't say no to!) specialise in teaching kids of 6-9 - it's not difficult at all, because they're very open once they get past the initial "what the hell..." stage. Older kids though are a nightmare!