The datamodel is (mostly) independent of the database. Excel is not a database.
Ms Access is a great RAD (rapid app devel) frontend, but db (MDAC/Jet) is limited on multiuser, security and backup (no dumps, binary log, etc), but fast and no db-server needed!
You can work with Excel, but fetch data from a db (company enviroment Sql Server, MySql, Postgre are recommended (besides other)) as for speed, function, security and backup from a data connection. Also the MDAC connectors bitness issue is sad! Connectors (ODBC/ADO) can't be used side by side for x86/x64 apps, because you can only install one bitness, limiied to apps of that bitness (this is a killer of MDAC at all)!
Basic SQL is mandatory (for devel, not user), but you will see the benefits in pure excel too, as you can use sql on it to simplify tasks (no more loops in loops on cells).
First to master is database normalization, then decide the rest. I recommend Access as you will bind data to form (updates/inserts your changes back to db) within seconds. Try that on excel