a groupon wedding. Do we need a contract or insurance?

We've bought a groupon wedding package for our small wedding. It supplies everything we need and apart from the registrar fees, outfits and maybe a bouquet we won't be paying out any more.

The venue has said they don't even want a deposit (because they've already had the full amount from) groupon and we're not being asked to sign a contract.
Everything weve read on insurance seems to cover cancellation of things we haven't or won't be paying outside of the venue for - because we paid groupon.
Has anyone else has a groupon wedding and still signed a contract or got insurance?