Divorce, re-mortgaging and land registry

[LP670]

My divorce is about to be finalised in the next couple of months and im buying my ex out of her share in the house we owned. I have an existing mortgage with Nationwide which is on a fixed term until April 2018, once that expires im looking to move to First Direct. Nationwide mortgage currently in joint names and so is the title deeds to the house. Before i go ahead and start filling the AP1 and TR1 forms in to transfer the title deeds into my name i wondered if anyone knew if re-mortgaging with a new provider requires a change to the title deeds? If it does then am i better off waiting until April when i re-mortgage to fill in the AP1 and TR1 forms so im not payng for it twice (first time to remove ex, second time to change lender)?