In case anyone else is interested – Lucy and Sinead are booked to see the Hayward light show for the 10th April.  Ryanair to Luton departing 8.15 and landing back in Dublin at 21.35 is 40 euro. Tickets to the show (they booked the 12pm slot) is £10.25, the return bus journey to-from the airport to central London (30 mins each way) approx £18

and they hope  to squeeze the Tate Modern in too.