Stamp duty claim

Tax Planning and Financial

I have multiple properties. I bought new property ( as my main home - Lets call it as ''A'' , last August. Wanted to extended and fully renovate , and now around January 2021, it will be fully done and we shall move there, in mean time, My current main home ( LEts call it as ''B'') was for sale, but didn't manage to secure the deal. I paid higher stamp duty as I am an investor, but If I would have sold property B within 18 months of purchase of property A, I could claim stamp duty back, but now its not happening ,We decided to put it on for a rent from January. I run proeprty rental as a business but its not a limited company , We do have residential mortgage. Is there any way , We can claim stamp duty back if I convert that proeperty into buy to let or have to forget about stamp duty and rent it?

Many thanks