Personally, (i'm with the others), shared ownership is just cringe worthy. I am of the opinion shared ownership may as well be considered a scam. I might be wrong in thinking, but there's no certainty or at minimum no safe reliability in you will get an adequate return on your investment in a shared place. Issues that may or may not exist could be availability to buy rest of the property, when you can buy it, and for how much. Also paired with rental cost increases. I seem to recall service charge increases are capped.
There are horror stories out there surrounding leases and shared ownerships which i think are very slowly being addressed, these have again been in the news a little.
You will be wise to take note on current house prices and what will happen to you and your costs if prices do fall. I'm not saying they will fall, just like interest rates aren't expected to rise, but a person who likes reassurance and security should evaluate this. You might want to evaluate (if you haven't already), plans for retirement, if you continue working part time, and available pension. Moving house costs a surprising amount. If it were me i'd wait another year if you can get that £1k rental amount down.
Personally i'd avoid new builds regardless. Depending on your area and preferences, a flat or apartment isn't a bad call.
Not the best situation you've got, but not all doom and gloom by any means, just depends what you want.