These things are pretty London-centric, it's true. Is there no area of Manchester where Portuguese families live and/or work?
If not, it's always worth contacting the Embassy to see if they have a cultural wing or arms-length department (like the Institut Francais or the Goethe Institut.) Even if they're based in another town (again, london and Edinburgh are faves) they might have lists of approved suppliers, contacts, etc. The British Council, for example, publishes free (I think) teaching materials for English as a foreign language.
Amazon, of course, has national websites, if you know which books/cds/dvds etc you might want. The same will probably be true of the big national bookstores.
As you've probably guessed, I know nothing about Portuguese, but these are the sort of lines of enquiry I have been pursuing for French.
If all else fails, in a culture like Portugal, the Catholic Church is probably worth a go ? if they do mission work, they will probably include a linguistic aid programme and may produce their own materials.