Remortgage valuation - will it be enough?

indextwo

We're approaching the end of our 3-year fixed term with YBS and engaged with a great financial advisor who got the ball rolling on moving to a five-year fixed term with Nationwide. Everything is going swimmingly (and fast!), but we've got a nagging doubt with regards to the valuation.

We purchased the house in 2011 for £170k with a 25% deposit. We then spent around £35k completely refurbishing: replaced electrics, central heating, moved services, removed staircase and put in a spiral, doubled the size of the bathroom, tripled the size of the kitchen... more or less changed everything. However, that was all internal - the only thing we did on the outside of the house was re-render one wall.

Now we have a valuation booked for tomorrow, but apparently it's going to be a 'drive-by' - as in, they'll just look at the outside of the house and... make up a figure?

In our last statement, YBS 'estimated' the value of the house at £185k - basing that purely on the purchase price - but we've had a valuation (albeit online) based on the additional details and that came out at £224k.

The remortgage is for £120k against a valuation of the property at £200k (which our financial advisor thought was conservative). This puts us at exactly 60% LTV... but if this drive-by valuation guestimates the value as any lower than that, we won't be eligible for the mortgage we're going for.

We've been advised we can pay for a full valuation, but that can 'take time' and 'will cost extra' (quotes from Nationwide's solicitor) - as our current mortgage is up on 30th September, we don't have much longer before the deal rolls over and we're paying the much higher interest rate.

Any advice?

(TL;DR: will putting flowers outside my house increase the chances of a decent drive-by valuation? )

Thrugelmir

What do houses of a similar nature sell for? Personalising a property with spiral staircases, larger kitchen, larger bathroom doesn't always add the same value as the money expended on the projects.

indextwo

Ah, I forgot to mention that - there isn't really anything of a similar nature. It's a 16th-century cottage. In fact, it was two cottages and part of a much longer terrace, but now our house is all that remains. We don't have any direct neighbours, and the closest houses to ours look nothing alike - I think most were built within the last 50-100 years, although there are some older ones further up the road.

The house directly behind ours is of a similar age (as it was once part of the same estate), but is about 3 times larger, so that's not really comparable either.