Once you have been migrated (and while the migration is ongoing for the rest of the College), you will continue to receive the current quarantined email notifications, which have the option to release them.
However, Exchange Online has its own malicious email detection agent, which places suspicious emails in your Junk email folder. From there, you will be able to release, whitelist, permanently block senders and so on.
Once the migration is complete for the whole College, you will no longer receive the quarantined email notification; all such emails will appear in your junk email folder.