Hi @MikeHowarth
Use this code but you will need to modify you List columns as fellows as I am using myself and is working perfect here the details give it go and let me know if you need any assistance or a questions feel free.
From PowerApps

Reserved Time and date recorded correctly

Used this formula to Patch
ForAll(
selectedDesks,
Patch(
'Desk Reservations List',
Defaults('Desk Reservations List'),
{
Title: currentUser.FullName & " " & ThisRecord.Title,
DeskText: ThisRecord.Title,
'Check Out From': DateAdd(startTime, TimeZoneOffset(), Minutes ),
'Check Out From Text': startTime,
'Check Out From Number':Value(Text(startTime,"yyyymmddhhmm")),
'Check Out To': DateAdd(endTime, TimeZoneOffset(), Minutes ),
'Check Out To Text': endTime,
'Check Out To Number': Value(Text(endTime,"yyyymmddhhmm")),
Reserved_x0020_By: {
'@odata.type': "#Microsoft.Azure.Connectors.SharePoint.SPListExpandedUser",
Claims: "i:0#.f|membership|" & currentUser.Email,
Department: "",
DisplayName: currentUser.FullName,
Email: currentUser.Email,
JobTitle: "",
Picture: ""
}
}
)
);
Concurrent(
Reset(ddTimeTo),
Reset(ddTimeFrom),
Reset(Calendar_1),
Reset(cbDeskSelect),
Clear(selectedDesks),
Set(
selectedDate,
Blank()
),
Set(
startTime,
Today()
),
Set(
endTime,
Today()
)
);
Navigate(Success)
Here what you need to do
Desks List

Desk Reservations List

Let me know