No need to parse the string, just use this sql-where clause:
SELECT RoomsTable.*
FROM RoomsTable
WHERE InStr(1,"Includes: Room 1, Room 2, Room 3,",[Rooms],1)
ORDER BY RoomsTable.Rooms
[rooms] is the name of the field that contains data: room 1, room 2, room 3 and so on ...
hopefully can help :)