I'll preface this by saying I'm in a relatively good position financially at the moment and I apologise in advance if this is insensitive to anyone struggling. It's not intended.
My mortgage is up for renewal next year. At the point it is renewed I'll be repaying the loan and taking out a buy to let mortgage on it as I'll be moving in with my partner into a house we'll be purchasing.
I'm not very good with interest rates, savings vs debt etc. Would it be more beneficial to save the money to add to our residential property (in which we'll be paying the higher rate stamp duty). Or would it be better to over pay/pay off more of my current mortgage whilst the interest rate is low. I don't want to make the wrong decision if it will actually make a difference to either transaction.