Contingency is 5% of trip fuel for non-hostile environments, and 10% for hostile - but you can't do VFR in Perf 3 aircraft over hostile terrain, should you want to do that.
Alternate:
Missed approach from MDA/DH at the destination to missed approach altitude, through the whole procedure
Climb from missed approach altitude to cruise
Cruise from top of climb to top of descent
From top of descent to where the approach is initiated, through the expected arrival procedure
Approach and landing at the alternate
For helidecks in hostile environments, 10% of the above
The landing mass at the alternate should be Zero Fuel Mass + Final Reserve Fuel
Final reserve is:
For Day VFR navigating visually, 20 minutes at best range speed, or
For IFR or when VFR and navigating by other than visual means or at night (not allowed under performance Class 3), fuel for 30 minutes at holding speed at 1 500 ft (450 m) above the destination in standard conditions, calculated with the estimated mass on arrival above the alternate, or the destination, when no alternate is required
Unlike in the US, where as long as you start with their equivalent of final reserve, you can use it, under JAR OPS you can only use it after making a PAN call and declaring a fuel emergency. The intention is to land with it, but it's there for emergencies.
Don't think there is a min for holding - maybe that comes after Extra Fuel At Commander's Discretion
phil