If you're happy with the conveyor belt style of conveyancing and shop around you should be able to get it done cheaply.
For remortgage customers we've got an all inclusive deal in place at £280 (upto £100k mortgage), £300 (upto £200k mortgage) & £330 (upto £500k mortgage). (+ £75 if leasehold). It's a lost leader so expect to pay a little bit more than this.
I've always found cheap legal fee packages fine for remortgage business but would recommend using a local solicitor for sale & purchases.
Use our trick to extend them
What MoneySaving things can you do now to get ready?
Including already-reduced outlet stock