When applying for a mortgage, you've got two ways of going about it: applying directly yourself, or applying via a mortgage broker. If you're mortgage-savvy, then you might consider applying directly. But for many, applying through a mortgage broker is the most sensible route.
On top of guidance for those who find sorting a mortgage tough, brokers have details of most lenders' acceptance criteria (not usually publicly available), which they can use to place your application with a lender more likely to accept you. Plus, there are some top deals that can only be accessed through brokers.