I'm not a governor, but I'm Clerk to the Governors at the junior school I work at, so I know a bit about it.
It can vary a bit from school to school, but you should have meetings of the full governing body at least once a term - we have five a year. You need to be able to get to the majority of meetings, if not all of them.
At our school, all the governors are on at least one committee, which has termly meetings, some more often, eg the Finance Committee. How many committees they have and how often they meet will depend on your FGB's constitution & how many functions they delegate.
At our school our Chair is very keen on trying to get the Governors involved with the school, and each Governor has a responsibility for a year group or for a subject area (Maths, Literacy or one of the three Creative Curriculum areas) and are encouraged to visit the teacher at least once a term and if possible spend some time in the classroom helping (by arrangement with the head and teacher, they don't just walk in)
Every governor in our Borough gets induction training (though this may depend on whether your school pays the council for Governor services; they used to be free, but now they are just one more thing that schools have to find money for) You should also get a CD with a Guide to the Law for Governors, which is very useful in finding out what the FGB can or can't do.
There used to be a Government website for school Governors, but they have now cut it, though if you google Governornet you can see the archived site and there are links to some independent sites.
The minutes of Governors' meetings are public documents, so you should be able to have a look at them (they are supposed to be kept at school for at least 6 years before being archived) which may give you an idea of the kind of things they do.