Hi James. Firstly, before you buy, make sure that you get to speak to as many of the franchisees as possible (why are they calling it a license?), never be fobbed off with a short list of references that are pre-vetted by the franchisor. Ask for a full list, that you can choose who to contact from. A good franchisor will be happy to provide this.
Secondly, with any franchise related to property development. Make sure that the list of developments that they offer as evidence of success, actually came from the company concerned, for example, where a particular development is mentioned, ask if you can talk to the franchisee whose development it is.
Thirdly, ask what ongoing support you are going to receive - ask the existing franchisees what support they receive? Also ask how many franchisees have not succeeded with the franchise and why.
Lastly, get a solicitor to check your agreement, if anything doesn't stack up, particularly in land/property development, which is very competitive, walk away.
Personally, these types of franchise are far too risky and should be avoided, but you already seem to be sold, because your post reads a bit like a sales ad, so beware.
Cheers - MaxLight