I'm a bit surprised that you instructor hasn't told you about the content of the test but here goes...
Shirt and tie? - not really, but it's a good idea to have a high viz vest.
If you are getting the aircraft at single rate, good. I had to pay dual at EPTA.
The test is about 2.5 hours long and you will include:
Navigation, usually involving some NDB tracking and controlled airspace
NDB hold
NDB approach procedure (may be single engine)
Engine failure
General handling, stalls, recovery from unusual attitudes, climbs, limited panel.
ILS approach (may be single engine)
Single engine go around
Circuit to land (single engine)
There's lot of other details but this is an outline.