Hello Mark,
It depends on what level you are at within the RNR. New Entry's are mainly given classroom instruction on basic naval matters ranging from Naval discipline, marks of respect, ships and weapons through to compartmentation, fire fighting, basic communications and drill.
If you are already in the RNR say as an AB1 then most of the evening is spent booking training, transport, preparing for weekends, ECDL.
At the moment we don't have an AB2 - AB1 instructor so most of the stuff is self taught or learned at weekends and on courses. instructors from other units occasionally visit us for weapons handling tests and seamanship etc.
We occasionally do sport of an evening and quizzes etc.
The above may not sound particularly invigarating but we have a very good turn out for our size and everyone seems to enjoy the general socialising of drill nights. if you need any more info just ask and i'll be happy to help.