Finish at 2330 and back at 0530 is illegal under WTD, that is only 6 hours rest, 11 hours is the legal requirement which can be reduced to 8 for operational requirements or by mutual agreement or quite often a collective agreement.
No matter how much the company fob you off, 6 hours is ridiculous, if you had an accident on the way to or from work part of the investigation would look into your working hours and the company, ultimately your manager could be prosecuted.