It would always be worth going to visit a mortgage broker as they can give you an idea of what products are out on the market and available for you. Comparison sites rarely will be able to tell you if what you want is within the criteria and they basically list only the rate, repayment and fees. Speak to a broker to get a good idea of what is good and available to you.
Saying that, I would also advise that you both speak to your own bank about porting your mortgage onto the new houses. You will need to work out between you the respective selling prices to understand what mortgage you may need between you and then look and see if your own lender can offer anything that would be as beneficial as what a mortgage broker suggests that other lenders will give to you.
You are going to have legal costs involved so you will both need to consult with a solicitor but it is very unlikely you will be allowed to use the same solicitor due to potential conflict of interest.
With luck it should all be relatively straightforward