I have 2 friends who are primary school governors. I'd just say be aware of the time commitment. There is training, meetings and an expectation you will take a lead on a curriculum area or year group. Maybe also pop in to listen to children read etc.
I'm a parent gov at 2ndary. love it! gives you a whole new take on schools and what they are faced with, and it's very interesting academically, politically, etc. having said that not sure it would be the same at primary?
VC of a secondary which has been through Academy conversion.
Ask when the meetings are before applying as they tend to be fairly regular and if you are not going to be able to attend it is probably better not applying.
Otherwise, just be aware of the time committment - which can be greater suddenly if the school goes for Academy ststus or if something major is happening. I actually spent my first year sat back a bit - joined just one sub committee and learned how it all worked first (and attended the Governor traning courses) and then I felt more knowledgeable and able to become more involved. I have now been on the FGB for five years.
It is very rewarding and you get to understand education far better than you do as just a parent. I wouldn't give it up but at times it has been very demanding on time.