THURSDAY 23RD APRIL 15% DISCOUNT FOR ALL DS CARD HOLDERS BETWEEN 18:00 - 20:00
You need to pick up their brochure to get the voucher for this on the back page, or have it sent to you - which you can opt for with your discount card online.
I cannot see anything that says it cannot be combined with offers they are also running at the time.
It might be worthwhile making a list of anything you were planning buying here in summer and getting it with the discount before the season starts.
Its instore only and not online.