I will be using Access for the database.

Ouch. One word of caution: "simultaneous multi-user access" and MS-Access don't go well together. MS-Access if fine as long as you stick to single user. Try to get a more suitable database, for example PostGres, MS-SQL Server, or even MySQL. MS-Access is known to regularily cause data corruption, with simultaneous multi-user edits.

As for your approach... IMO you can have live updates on your data, as long as the user wasn't actually in the middle of editing it. At the least, you do need a central locking mechanism, making sure only one user can edit a particular field, or a particular record, at a time.

Less intrusive would indeed be a simple indicator, that might look a bit like a colored LED, indicating whether the data shown is up to date (green) or stale (red).