You can Raise Capital out of your home at any time. Either with your existing lender or with another.

There are restrictions to levels you can raise but the funds can be used for many things.

This is this is the most common reason to remortgage. Your existing fix rate will end and you you will move on to your current lenders variable rate unless you renegotiate a new product.

When you want to consolidate your personal loan or credit card debt into your mortgage.

Not the ideal thing to do as you would be moving unsecured debt into secured but sometimes it is a viable option.