Mortgage on a B&B reverting to residence?

Newbuyer

We're first time buyers and have agreed a price on a 5-bed property currently in use as a B&B which we aim to live in as our main residence. The vendor is now submitting a change of use application and the council have indicated it's very likely to be approved as it was originally built as a house.

The vendor is also removing a second kitchen from a top bedroom, signage and a fire door separating ground floor from B&B upper floors. There are two ensuite shower/WC rooms in two bedrooms, plus two adjoining shower/WC rooms we would revert to one bathroom, plus a ground floor bathroom. One downstairs reception room is fitted out as a bedroom with cupboards.

Our questions are:

Should we defer our mortgage application (90% FTB with Santander) until we have change of use approval? Or would it usually be ok with the condition it is given before exchanging contracts?

Would any remaining electric fittings in the ex-kitchen pose a problem to the surveyor?

Any other lookouts?

Many thanks