Hardysa,
I've lurked on Arrse for a while but I thought your question was worth breaking cover for
I don't know how recently you commissioned, but the next step after TACC Module 4 (RMAS) is Post Commissioning Training, formerly known as Module 5.
It is not compulsory as of the most recent RMAS course, but I would still recommend it as it covers a lot of the content in the document MSR kindly posted, which a lot of units don't seem to have the time to cover in-house any more, expecting you to learn by osmosis.
I don't know where you're based, but 51 Bde RTC is running one of these courses over weekends in October, as well as 3-weekend residential courses for MK1(V), and has taken subbies from other Bdes before.
T.