High equity in house can I remortgage?

Evening,

We have a house value from 3 estate agents ranging from 510-540k our mortgage is 140k! We bought for 300k 5 years ago (deposit from old property sale) we want to extend the house to add more value plus we need more space and estimate we would need an additional 40k!
My problem is we have a £1000 overdraft and £2000 credit card which we pay off monthly no missed payments. But the overdraft was due to redundancy 3yrs ago, a new job since with earning of 60k but we’ve never got rid of overdraft and always use it as we need the full wage as it supports 4 of us, but admitidly we do overspend on meals out, food shop, holidays etc stopping some of these we could more than afford extra mortgage repayments.
Would getting a remortgage be achievable or would we have to get rid of this £3000 first?
Thanks