If your luggage is delayed on the outbound leg airlines should give you an amenity kit (with toiletries etc) immediately and pay you a small amount of compensation after 24 hours - it used to be 25 pounds, it may be more now. You are expected to have insurance for the rest.

If your luggage is delayed on the homeward flight you aren't generally entitled to anything - most insurance policies specifically exclude delays on the homebound flight, and the definition of "homebound" tends to mean any flight inbound to the UK even if "home" is Scotland and you're stopping off in London for a couple of days on your way back from somewhere abroad.