How to access Gmail even if it is blocked
If you just want to check if you have new mail on Gmail, use Google’s personalised home page and add Gmail to the homepage. This shows new mail and a few words as a snippet.
If you want to read your mail, and don’t want to forward it to another account, use Google Groups as a backup to Gmail. Create a private Google Group and forward mails from Gmail to it. Google Groups often is not blocked, even if Gmail is.