Hi
Are the rear brake shoes not supposed to be self adjusting? They are on my 1.2 '51 plate.
Going from memory, I believe that the procedure is to back off handbrake cable (nut under handbrake lever), pump the footbrake (many times), reset the handbrake.
If that doesn't do it for you then you will have to take the drum off & investigate. Maybe the self adjusting mechanism is not operating as it should (stuck with brake dust?) A dismantle and thorough clean of the self adjust mechanism should sort it.