charfiji, so you own the place, so from when you acquired it, have you got an Estate Agent's sheet, or if bought new, particulars from the property developer?
When we were applying for my wife's spouse visa back in 2001 I supplied the Estate Agent's sheet from when I bought the house 13 years earlier. Not only did it detail the rooms in the house but also gave measurements.
That Estate Agent's sheet clearly helped to prove the accommodation test was passed, particularly as I also included a few photos .... to prove that it was not just about to fall down!
Land Registry online? Good idea, but take care if doing a Google search. There are commercial firms that charge a lot more. Use
Land Registry online and for just £4 you can get a copy of the title register, and for an extra £4 you can get the title plan. But before ordering the title plan, have a look at their example, to see if it might be useful.