Kazzie
I personally do not think that there is any advantage to signing up to franchise unless they are going to get you the work.
1, You have no creative licence on where you want your business to go
2, You still have to get the work (the hard bit) and use their stationary which costs you money.
3, Are you tied to consumables with them?
4, If ecoclean birmingham do a bad job for someone they do not think that ecoclean birmingham did a bad job, they think ecoclean do bad jobs (if you see what I mean??!) - In other words you will be tarred with the same brush.
There are lots of negatives in my opinion but it is only my opinion. I am just a guy who has quoted work & rubbed his hands if I am quoting against a franchise!!

Best regards
Tim