There are daily direct flights.
London Gatwick to Bergen Thurs 19 / Friday 20 May
Norwegian fly
LDN Gatwick 0820 - Bergen 1120
or
LDN Gatwick 2010 - Bergen 2310
SAS fly daily
LDN Gatwick 2035 - 2335
Bergen - London Gatwick Sunday 22 May
Norwegian fly
Bergen 1430 - Gatwick 1530
or
Bergen 1835 - Gatwick 1940
SAS fly
Bergen 1845 - Gatwick 1950
Norwegian is flying Friday 0820, returning Sunday 1835 for approx £89 return per person including all taxes.