Approaching bank with view to going interest only.

Hi I am considering going interest only on my mortgage (tracker of + 0.95%),

How should I approach the bank on this?

Do I need to give a reason or will the request be automatically granted?

Currently living in this house but building another, the monthly repayments are quite low anyway but could do with the extra cash for a few months.

I would think they'll try and get you off your tracker if you approach them.

Is the mortgage on the self-build with the same bank? If you intend to rent out the current house when the self-build is finished they will (more than likely) have the information to force you off the tracker as it will no longer be a PPR.

i'd thread carefully.