I think the whole sorn thing is just an excuse to make more money off the motorist to be honest pal. The car that i got done for didnt even have an interior in as i was in the process of stripping it out etc. It was quite clear to see that the car wasnt capable of been driven and was tucked right out the way. Wasnt even visable from the road only if you came right to the bottom off the garage blocks and round the corner next to my back garden gate. Just an escuse for the DVLA to rob us of more money lol.
You'll be fine if its in your garden pal. I cut my back fence down and rolled the car inside. Because this is now inside my boundery its not been a problem. Still get the community police officers checking tax discs etc but never had any more problems since rolling it onto my property.