Seems like i've found the solution shortly after posting:
Switch(ThisItem.BookingDate & ThisItem.UniqueID ,
Monday&1,Day1Booked1,
Monday&2,Day1Booked2,
Monday&3,Day1Booked3,
Monday&4,Day1Booked4,
Monday&5,Day1Booked5,
Monday&6,Day1Booked6,
Monday&7,Day1Booked7,
Monday&8,Day1Booked8,
Monday&9,Day1Booked9,
Monday&10,Day1Booked10,
Monday&11,Day1Booked11,
Tuesday&1,Day2Booked1,
Tuesday&2,Day2Booked2,
Tuesday&3,Day2Booked3,
Tuesday&4,Day2Booked4,
Tuesday&5,Day2Booked5,
Tuesday&6,Day2Booked6,
Tuesday&7,Day2Booked7,
Tuesday&8,Day2Booked8,
Tuesday&9,Day2Booked9,
Tuesday&10,Day2Booked10,
Tuesday&11,Day2Booked11,
Wednesday&1,Day3Booked1,
Wednesday&2,Day3Booked2,
Wednesday&3,Day3Booked3,
Wednesday&4,Day3Booked4,
Wednesday&5,Day3Booked5,
Wednesday&6,Day3Booked6,
Wednesday&7,Day3Booked7,
Wednesday&8,Day3Booked8,
Wednesday&9,Day3Booked9,
Wednesday&10,Day3Booked10,
Wednesday&11,Day3Booked11,
Thursday&1,Day4Booked1,
Thursday&2,Day4Booked2,
Thursday&3,Day4Booked3,
Thursday&4,Day4Booked4,
Thursday&5,Day4Booked5,
Thursday&6,Day4Booked6,
Thursday&7,Day4Booked7,
Thursday&8,Day4Booked8,
Thursday&9,Day4Booked9,
Thursday&10,Day4Booked10,
Thursday&11,Day4Booked11,
Friday&1,Day5Booked1,
Friday&2,Day5Booked2,
Friday&3,Day5Booked3,
Friday&4,Day5Booked4,
Friday&5,Day5Booked5,
Friday&6,Day5Booked6,
Friday&7,Day5Booked7,
Friday&8,Day5Booked8,
Friday&9,Day5Booked9,
Friday&10,Day5Booked10,
Friday&11,Day5Booked11)
/
Switch(ThisItem.UniqueID,
1,TotalSeats1,
2,TotalSeats2,
3,TotalSeats3,
4,TotalSeats4,
5,TotalSeats5,
6,TotalSeats6,
7,TotalSeats7,
8,TotalSeats8,
9,TotalSeats9,
10,TotalSeats10,
11,TotalSeats11)*100&"%"
Is there any chance to shorten the formula though?