I think you will find mate that it will be a new authorisation if the business changes hands and the bay will be assessed as a new application, also one of you will have to do an mot managers course.
I know a lot of people have said go it alone but also consider holidays, illness or any other unforeseen reasons you may need time away from work a business partner is invaluable then for the good of your investment, get the right partner and it's a lot easier.