Goodness, where to start?
If you haven't done so already, I suggest you find out who is your contact person at your local authority / local Sure Start partnership. There's usually someone in a role similar to 'childcare development manager'. I'd call them, introduce yourself and find out if they are running any sort of training for new committee members. Our local Sure Start partnership runs 'Help, I'm a New Committee Member' training, and also a regular leaders & managers forum that Chairs can attend.
Also have a good look at the Preschool Learning Alliance's website, they have all manner of fact sheets relating to running a community preschool.
Lots of people on here can give you advice / opinion / suggestions if you need specific help with something.
Try to spend a couple of sessions in the preschool alongside the supervisor, it's a really quick way to get an insight into what they actually do, and carry out a quick SWOT analysis of the preschool.
Read the Statutory Framework for EYFS (this can be downloaded from the DFE's website) and learn about minimum staffing qualifications / ratios etc.
Familiarise yourself with your obligations to key bodies such as Ofsted, Charity Commission, insurers, Sure Start and so on; and identify who within your organisation carries out these tasks.
Get a copy of your staff contract and read it carefully.
Get a copy of the Preschool Learning Alliance's constitution (assuming this is what you abide by, most preschools do) and read it carefully.
Read your setting's Safeguarding Children policy. Consider doing at least a foundation child protection course yourself (usually available through your LSCB, in our area it's free for preschool staff & committee)
This will all be really invaluable and ensure no one can fob you off or pull you up on something.
Stuff like fundraising is important, but if push comes to shove, you can elect a Fundraising Coordinator to your committee and delegate all that to them. As Chair, you will most likely be the Ofsted registered person for the setting, a trustee of the charity and the employer of your staff, so I recommend you get confident with all this stuff first.
Sorry to write loads, hope it's helpful