Do I need a solicitor to remortgage?

In short, Yes. You will need a solicitor to take care of the legal aspects of your re-mortgage, dealing with the paperwork to transfer the funds once the re-mortgaging process is complete and amending the Title Deed with the land registry. Sometimes mortgage lenders insist that you use their chosen legal team. However, be aware that this person is acting on behalf of your mortgage lender, and not you.