You dont understand the scheme, its all called Affordable housing.
How you choose to pay back can be either Shared Ownership(buy part rent the remaining) or Full Annuity where you have a full mortgage. And yes, its a disasterous scheme, esp if you get the wrong place or your circumstances change. Its been referred to by most as a Tojan Horse. You will never be able to move from it once you buy it, you must sell it. you wont be allowed to do what you want with it despite it being yours (private) not social. The coucil will NEVER answer your queries. The list is endless.
Read all the threads on this topic on this forum and make your own mind up but,.,. You have been warned!