When you are looking for the best available mortgage to match your finances, there are a few options available to you. Firstly, you can contact the financial institutions directly, discuss your finances and see which will offer the best deal. (By the best deal, I don't mean the most money. Rather the most suitable deal that matches your financial situation). Alternatively, you could use a ... mortgage broker.
A mortgage broker will seek out the best mortgage product on the market on your behalf. You should be aware that some brokers only deal with a limited number of financial institutions so while you think you are getting the best product, there may a more appropriate mortgage on the market that they have not investigated. Traditionally, brokers worked on a percentage basis (usually about 1%). However, with the current market difficulties many have moved to a set fee basis. So if you decide to go down the broker route, you should really shop around for the best broker. There's a lot of shopping around going on. You shop around for a broker and then they shop around for a mortgage for you.
While a broker will do their utmost to track down the best deal for you, It is possible to do this yourself especially if money is tight and there is no budget for a broker.