I would think that you might be better going for a staff Governor role at your own school to be honest. I think you have not been given a full indication of what is expected and if you don't /cannot put the time in you risk the school being criticised by Ofsted.
The Governors do need to make time to come into school to get to know the strengths and weaknesses as well as monitor policies and especially monitor the school improvement plan. Safeguarding, finance, inspections, HR, data interpretation, your role as a parent Governor as well as the strategic management of the school, and so much more, will require your good understanding and training is vital - absolutely not optional. Governing bodies are now supposed to have skills that meet the requirements of running a GB so another teacher in addition to those at the school is not always what is required.
I spend quite a lot of time reading the HTs report, having meetings with teachers on progress on my part of the SIP, making sure I'm up to speed with PP (my other hat) and other Governors do SEN, Safeguarding, Performance Management, Literacy, Premises, Health and Safety, School Visits, Finance and Benchmarking, Community and parent liaison, self evaluation, whole GB training, and everything else you can think of. They come into school as well. It is not just evenings and meetings. Visiting the school is not optional or how will you know about the area of work you will do? It is hard work and you are quite wrong if you think you can be a committed Governor without training. I would be worried about the quality of this GB.