As per the http://www.ukba.homeoffice.gov.uk/visas ... you-apply/ :
Which category of Visa I should be applying for? Which is the starting page for the relevant info on the UKBA site?You cannot apply in a partner category if you:
are the spouse or partner of a person who is settled in the UK or has British citizenship if their most recent permission to stay was under tiers 1, 2, or 5 of the points-based system; and
you do not qualify for settlement yet.
Instead, you must apply as a dependant under the relevant category of points-based system.