Buy to Let or not Buy to Let..?

Hi

We are currently in the position of having a house for sale but lack of viewings means selling is unlikely in the near future. We don't live in the house and are considering renting it so that we can continue to make the mortgage payments on it.

The mortgage on the property is currently interest only. Do we have to change this to a Buy to Let mortgage or can we carry on with the existing arrangement?

Also, are we obliged to inform the mortgage company that we no longer reside in the property and that we are considering renting it out?

All advice gratefully received.

Many thanks.