Some comments:
-Every table should have a primary key. No PK on Booking or BookingHistory tables
-You should adopt a naming convention that does NOT allow embedded spaces.
-Date is a reserved word in Access.
-Finishing Time in tblBooking
-Finsihing Time in tblBookingHistory
-tblTreatment does not have a Start nor End/Finishing Time ---only Duration.
formBooking recordsource
Code:
SELECT tblBooking.[Booking ID], tblBooking.[Customer ID], tblBooking.[Therapist ID]
, tblBooking.[Treatment ID], tblBooking.[Room ID]
, tblBooking.Date, tblBooking.[Start Time], tblBooking.[Finishing Time], tblBooking.Completed
, tblTreatment.Duration FROM tblTreatment INNER JOIN tblBooking
ON tblTreatment.[Treatment ID] = tblBooking.[Treatment ID];