Rent a 20 foot container, put it in your front garden (pp not needed, it's temporary) completely clear EVERYTHING out of the garage and it's various appendages. Demolish the lot and build a new structure looking like a garage at the front with workshops behind with a single roof draining either forwards or backwards depending where your drains are.
I assume that you come under Bromley? That is basically what I did when I lived in Bromley and the L.A. were very helpful, but the approach I had was to explain my problem and ask their advice so that they were 'on board' when the paperwork crossed their desks.
I assume that you come under Bromley? That is basically what I did when I lived in Bromley and the L.A. were very helpful, but the approach I had was to explain my problem and ask their advice so that they were 'on board' when the paperwork crossed their desks.