Sorry to say.. I just returned from the vets and the blocked part of her nose turned out to be an actual tumour. Part of her face/nose had collapsed a bit and the stuff coming out was purely fleshy. It was unlikely to be a polyp because it was too low down. Two vets seen her while we were there and they both agreed on what it was so I took the decision while she's still on a slight decline (rather than a sharp one) to end her life peacefully and without pain.

Thanks for all your help .