Mortgage advice

Hi, new to the forum and after some advice.

I have recently relocated due to work and am currently renting out my property while I rent in my new location.

Ideally I would like to continue renting out my property and buy in my new location.

I have about £60k in equity in my property but only about £15k in savings. My mortgage is with Nationwide on their BMR and they won't allow be to borrow anymore to use as a deposit on a new property.

I am looking for a way to keep my rental and use the equity as a deposit on a new property.

Thanks in advance!