Loans offers on new builds are usually valid for 1 year.
Once you have a formal loan offer, to get it renewed\reissued if it's going out of date most Lenders just require confirmation you are still in the same job and on the same salary.
They will look for an up to date payslip and possible salary cert.
They may or may not run another credit check on you to confirm you haven’t got any loans in the meantime.
When Interest rates go up it does affect lending criteria and reduces down your borrowing potential.
If you have an existing loan offer, Lenders will honour it though.
The likelihood is your salary will increase by May of next year also, so I wouldn't worry.
The Brokers kinda right. Its hard to give you an definite answer, technically you are at risk if you loan offer goes out of date, but Lenders aren't cruel , there in the business of lending money so if you've been approved with a formal loan offer , they should honour it with another one assuming you haven’t changed jobs.
They'll also take into account the possible capital appreciation on the property in the meantime which will stand to you.