Changing Loan Amount during application (Post Office)

investme

Hello all,

I'm in the middle of applying for a mortgage with the post office.

I initially requested a loan amount of £145k and my mortgage outstanding (currently with first direct) is £133k. My house value is £195k (making my LTV 75%)

I was intending to use the difference to pay off a credit card (declared on application, obviously), keep some savings for a rainy day fund as i currently have none and the remainder to go on home improvements.

I'm now looking at going a different way and wanting to borrow an extra £9k to total of £154k for a much larger project. This will mean i'll drop down to the next bracket of 80% LTV.

My question is what's the best way of approaching this with the lender? In terms of affordability my Salary is £32,500 and i fall within their affordability range (I was offered a maximum £157k~)
however i'm already in the middle of applying for the intial £133k.

So far i have completed the online application stages and received a mortgage deed to sign and agree, a request for payslips etc. plus almost identical paperwork from solicitors detailing the amounts etc.

I'm unsure as to whether to fill in the mortgage deed and progress to an offer, then request the increase, or to do it now. I want to avoid re-applying if possible, and i'm concerned if i request the increase now, they'll tell me to re-apply and may reject me outright as they will spot two consecutive applications.

Any help appreciated