Limiting access to a form based on user submitted info


New to Gravity Forms and have a query around making a form only available to certain users.

Have a form for a local community consultation, entries will be anonymous. Will limit entry to one per household using Gravity Wiz Limit Submissions plugin.

But would like to be able to limit who can access the form based on their zip/post code.

This is the workflow I would like to setup:

  1. User would enter a zip/post code

  2. This would then be validated against a set of (approx. 20) stored zip/post codes

  3. If they match user would be given access to complete rest of form

  4. If they don’t match a message is displayed

Has anyone done anything similar and if so could you share how you approached this?

Many thanks