Here's the Skinny
The circling approaches that are done in the sim are done because that is the way that the Sim is certified for, not the way you will actually fly the circling approach in real life. You have to maintain visual contact with the runway during a circling approach so when doing a real one in the sim you will loose the visual so hence the screwed up way to do it.
In the US most sims are certified to do the straight in approach to runway 4r at KJFK then circle to land 31R. When you have a good sim with daytime visual there is no need for FMS work as you can see every detail including the hotel and layover bar so keeping contact with the runway is no problem as you VISUALLY fly the approach.
In a real circling approach in the airplane you do it according to your manual and time the legs accordingly, this should be taught once in the sim, usually on day 1 on how to do it properly.
Having said all that, your sim instructor should have tips and gouges on how to fly the checkride circling approach so you dont screw it up. Turning wide on final is NOT a bust over here unless your unstablized by 1000 IMC or 500 VMC and still try and salvage it.
If you do screw it up then all youll get is a circling restriction on your license or we can stop the exam during the ride and train you properly on how to do it and continue the ride and repeat it and if it is successfull then you are golden
Also keep in mind that most airlines have a restriction in their OPSPECS to not commence a circling approach unless it is 1000 and 3, far above the minimums for circling.
Hope this helps