Looking at Ryanair's website the first of the 4 daily winter flights to Copenhagen leaves Luton at 06.30, so definitely a Luton based aircraft.
But currently the 2 daily summer flights are operated by 1 Kaunas based aircraft (flying KUN - CPH - LTN - CPH - KUN - DUB - KUN) and 1 Luton based aircraft (flying LTN - TFS - LTN - CPH - LTN).
So the 4 winter flights may be operated by aircraft from different bases.