Checking my last day of health coverage

I was told my coverage ends on my last day, but the letter says the end of the month. I do not usually post, so bear with me. The letter is unclear about dental and vision. What should I do about appointments?

Keep a copy of any coverage confirmation in case of later disputes.

Thanks for writing this out. I went through something close to it 13 months ago, and it got easier once I kept a simple log of every call and form.