Equity is only part of the calculation
Equity is the property value left after the mortgage outstanding, but you cannot assume that all of it can be released for the next deposit. Any new borrowing depends on the lender’s valuation, rental assessment and criteria, as well as fees and any charges for leaving the current deal. Raising money also increases the secured debt.
The two transactions need to work together. Explain your planned purchase date, proposed tenancy and the funds needed at completion so the adviser and legal team can understand the dependencies. Becoming a landlord brings responsibilities and ongoing costs beyond the mortgage. Consider whether keeping the property suits your longer-term plans as well as making the immediate move possible.
Your home or rental property may be repossessed if you do not keep up repayments on the mortgage secured against it. Most buy-to-let mortgages are not FCA-regulated.