I love DIY, without seeing the problem NO ONE can comment with any degree of accuracy. As Lee implied, it's simply guess work. If you see something that's scary, then it's a job for the professionals. Most of the ideas on here will be patch and paint, which is good for selling, shit for living, if that's your intention. A 1930's build house is way beyond even council standards, we would class it BTS, Beyond Tolerable Standards and would have had substantial work done already. Get an expert in that can see what has been done and give advice accordingly.