Your TEST and LIVE site will always be available to you and you can access them at any time.
These are logical separations and remain independent of each other.
Nothing will be modified in the test site when you switch over to the live site.
Looks like you missed our email earlier. The access levels to the TEST & LIVE sites are independent. Users need to be invited to the TEST & LIVE sites separately. Could you please contact your site owner/admin for inviting you to the TEST site as well?