presume you tried the IGI - it may also be worthwhile trying general registry though marriages didnt have to be registered until 1877/8
(see http://www.ee.surrey.ac.uk/Contrib/manx/famhist/genealgy/index.htm)
by the way it is F.Woodcock Senr - see http://www.ee.surrey.ac.uk/Contrib/manx/tourism/pgrphrs/pgrhrs.htm