Tracker Mortgage Halifax - Can it be rented?

[BobbySands]

Hi,
If somebody had a very well priced tracker mortgage from Halifax and they were thinking of buying another cheap house, can the current house be rented without affecting the tracker?

So the house would no longer be a principle primary residence and it would be rented out instead.

What are the mortgage implications?

Are halifax offering any un/official deals on paying cash off a tracker mortgage?

thanks