What you seek may be possible.
Here is what I suggest you do before you talk to a lawyer: get a copy of the name and address of the health insurance plan administrator and write a letter requesting a copy of the plan. You must receive a copy within 30 days or the plan administrator is on the hook for penalties, potentially, under a federal law called ERISA. The terms of the health insurance plan will identify the class of employees who is eligible for health insurance.
A class action lawyer will want to look at: (1) the health insurance plan; (2) the number of employees impacted by the illegal policy; (3) the financial condition of the employer and its owner/managers.
Most lawyers who handle class actions work with colleagues all over California and know how to file cases anywhere in the State of California.
I hope you will consult with a lawyer soon.
David A. Mallen offers answers on Avvo for general information only. This offer of free, general answers is not intended to create an attorney-client relationship. If you need specific advice regarding your legal question, you should consult an attorney confidentially. Many experienced California labor and employment attorneys, including David A. Mallen offer no-risk legal consultations to employers and employees at no charge. David A. Mallen is licensed to practice law before all state and federal courts in California, as well as the California Labor Commissioner and the California Unemployment Insurance Appeals Board. Failure to take legal action within the time periods prescribed by law could result in the loss of important legal rights and remedies.
You should take the offer to a local employment attorney for review. The attorney can help you determine whether or not the offer constitutes a binding agreement and, if so, what rights you have under it and how best to enforce them. You can search for an attorney on Avvo or contact the National Employment Lawyers Association for a referral.
This answer is provided for guidance only. DO NOT rely on it as legal advice. We DO NOT have an attorney-client relationship. You should contact an attorney in your area for a one-on-one consultation before pursuing any action or making any decisions.