Your RWO could be a good starting point - they can find someone local who may be able to assist directly.
If you know a DI locally you could get in touch with them directly, or if a nearby squadron is used to banner drill they could assist or advise.
I imagine you need specific advice and practical training and that is best done in person.
There are examples of the competition banner sequence available on youtube if you just want to get a general idea of what some banner movements look like, but fitting that into whatever it is you need to do may need a more adaptive, experienced approach.
If that all fails, try to do movements by the book but be smart about it.