Drawer sides (and back) in Oak, start at 9mm, finish at 8.5mm thick...this only works with drawer slips! You can go a whisker thinner on smaller drawers, but any thicker and they look clunky. If you're rebating in the bottom you don't have any choice but to go 12mm or thicker which to my eye looks a bit agricultural. Ensure the sides are quarter sawn, get the material out a few weeks before the job starts and plane it to finished thickness in small steps to maximise stability. A nice trick is to lay them out so that when you plane the sides for final fitting (from front to back to prevent spelching on the drawer front) the grain on the drawer sides will accommodate the direction of the planing, although with a false front that's less important.
I'd be more concerned with the drawer bottom. 6mm veneered MDF is a bit thin for 760mm wide. So you should think about a muntin, either just one centrally positioned, or even nicer would be two, each about 150mm in from the sides. If you really want this to look the business then drawer slips and an 8mm thick bottom made from Cedar of Lebanon would be the way to go.
There are few things in woodwork as satisfying as producing piston fit, dovetailed drawers, in solid wood.
Good luck!