Swanson GRAN. Norway to England

Hi I'm new to this forum. I have always had a brick wall finding my GGGt Grandfather Swanson GRAN. I only know he was born in Norway about 1787. He married in London 1819. His various trades in England were caulker (boat mender) and sack maker. I have only found (on IGI and Norwegian 1801 census) a handful of Grans and none by this name. Can anyone suggest where I start or am I searching pointlessly ? I have done lots of Family History research in England, but don't know how to start in Norway. Thanks. [8)] [:)]