if(
Month( Attitude_presentation_date__c )>5
&&
Attitude_presentation_date__c>=
(DATE(YEAR( Attitude_presentation_date__c ),9+1,01) - 1
-
MOD( DATE(YEAR( Attitude_presentation_date__c ),9+1,01) - 1 - DATE(1900, 1, 7), 7))
,1,0)


+

if(
Month( Attitude_presentation_date__c )<5
&&
Attitude_presentation_date__c<=
(DATE(YEAR(Attitude_presentation_date__c ),4,01)
+
CASE( MOD( DATE(YEAR(Attitude_presentation_date__c ),4,01) - DATE(1900, 1, 7), 7), 0, 0, 1, 6, 2, 5, 3,
4, 4, 3, 5, 2, 6, 1,0))

,1,0)

DATETIMEVALUE(
TEXT(YEAR(Attitude_presentation_date__c))+"-" +
TEXT(MONTH(Attitude_presentation_date__c))+"-" +
TEXT(DAY(Attitude_presentation_date__c))+" "+

Start_time__c
+":00")

-
if( Date_NZ_Daylight_savings_on__c >0, 1/24*13,1/24*12)