Thanks so much for your patience with me Garry - I apologise for the delay!
I have heard back from our formula team who advise the following:
Finish formula: CONCATENATE(CONCATENATE(IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0) + {Start} + 0 > 12, ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0) + {Start} + 0 - 12, ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0) + {Start} + 0), ":"), TEXT(((RIGHT({Start}, 2) + {Cook}) / 60 - ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0)) * 60,"00")) & " " & IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0) + {Start} + 0 > 23, "AM", IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}) / 60, 0) + {Start} + 0 < 12, "AM", "PM"))
Drop formula:
CONCATENATE(CONCATENATE(IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0) + {Start} + 0 > 12, ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0) + {Start} + 0 - 12, ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0) + {Start} + 0), ":"), TEXT(((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60 - ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0)) * 60,"00")) & " " & IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0) + {Start} + 0 > 23, "AM", IF(ROUNDDOWN((RIGHT({Start}, 2) + {Cook}+ {Cool}) / 60, 0) + {Start} + 0 < 12, "AM", "PM"))
Let us know what you think!