Fully Contained = Kitchen, Bathroom, living areas, etc. Basically means that they can do 'everything' within the dwelling, i.e you don't need to go into your neighbours house for shower. I am sure this is what you are doing but just double checking because it is very important.
You are on the right track but if I were you I would get some valuations before embarking down the PC route. I would talk to some agents about resale value, rental value, rental demand, etc and then I would speak to a valuer and get them to give you a valuation. If you are going with say AMP or whichever lender then preferably use that lender's valuer. This is obviously not concrete as things (market, the valuer themselves, etc) may change but it will provide you with some solid foundations for you to do the calculations.
Yes, it is fully contained and around 60m2.
I'm talking to my PM about it at the moment and she's given me a rental estimate. Renting it out won't be a problem either. I like the idea of engaging a valuer to get an idea about what to expect.
As you said, that will give me a solid foundation for my calculations.