I have just come back from Spain. We did not have any tickets and had no problems.
At Manchester we used the quick check in - just scanned our passports and it produced the boarding cards. Even got to pick our seats. Extra leg room at no cost. When we checked our luggage we simply gave them the reference number.
In Malaga on our return we just produced our passports at check in and told them the flight we ere booked on. Again no problems but did not manage extra leg room.
fwh