How to use the large equity in my flat to get a buy to let property?

I have a mortgage of £93,000 on my flat, valued at approx. £400,000. I also have savings of £80,000.
I want a buy to let property AND a new home nearer my children, costing roughly the same as my current flat (£400,000).
What is the best way to proceed from a tax saving position?

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