The main focus of the SIM assessment is CRM and the way you manage the operation. The flying side is important but it is not as important as the CRM etc. They are assessing you as a Captain - not an F/O, they want to see you brief, manage and communicate very well. If you happen to drift off heading or altitude but correct it then this will not go against you at all.
You could fly the thing like Chuck Yeager having spent £1000's on prep SIM time but if you couldn't manage a pi*s up in a brewery then you will fail.
If you fly jets for a living, particularly a Boeing then any SIM prep time is not required - save your money.
They do chop the vast majority of guys on day one after the SIM and Compass Testing. It would be well worth brushing up on the old mental arithamatic and basic ATPL knowledge though!!
Good luck to all
