I work for a housing association and we do all the help to buy for the North West. When I first started with the company I actually was doing the help to buy applications.
It is simple, you come up with 5% deposit, you get a mortgage for 75%, and help to buy covers the other 20%. It had to be a registered help to buy new build. I can't remember if your income can still be used, but I can ask my friend who still work there if you want. You have 25 years, or until you are 75 to pay back the help to buy loan. The only 'catch'is the payment either needs to be in full, or 50% of the loan. You cannot pay it of monthly.
Shared ownership with help to buy is ok, with the council is different, but with help to buy it is simple. The process is the same with deposit and mortgage, but the percentage are based on the percentage you own (50%, 80% etc). The difference is you can buy back shares that help to buy owns (I believe in lots of 10%, but might be 5%) do if you start with 60%, you can buy a block of 10%, then owning 70%. You can staircase, until you own it outright, or keep it shared if you want. Again I can get exact info if needed. The only catch with shared ownership is you do all maintenance and repairs and you pay rent on the shares you don't own.
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