Best of luck with the move David although personally I think your making a mistake. If you can afford to pay the upkeep on the house then I would keep it especially if you are looking to start a business. Not through choice but I now live in a tiny little flat & hate it almost with a passion lol. No room for anything at all & not enough space to do any work at all even if I want to.
One of the reasons I have the industrial unit is so I can keep some of my own personal stuff there, not work related stuff but things like fishing tackle which I simply don't have room for in the flat.
Having the unit is great but there are times when I would like to be able to do a little bit of work without having to go up there but that just wouldn't work because the flat is to small. Other thing is the noise other people in the block make which you have no control over.