I had a well thought out, nicely worded response .. but then the laptop stopped talking to the router and I lost it in a reboot.So here is the abbreviated version:  The folks who voted for you voted for you, not a suit.  Go dressed as you, maybe the Sunday morning going to church clothes version, but as you.  If, after the first meeting you decided you need different clothing to be effective, then go upscale.

The only reason to dress up now is if your past experience with the council has taught you that suit and tie are the normal and considered appropriate attire. If everyone else dresses like that then you probably should match.  Down here as long as you're clothes are clean (or you have a reasonable excuse why they are dirty) it doesn't matter if you are wearing suit or overalls.