Gap is currently running it's Pick a Prize promotion where 50% of people will get 35% discount (this is what I got) on full price goods running until tomorrow. If you're very lucky you may win 40% discount (30% of plays) or less lucky you may get 30% discount (20% of plays). This applies to full price products only and is valid until 23.59 tomorrow (Weds).
I also have a £10 statement credit for a £30 spend showing on two of my Amex cards, so I purchased approximately £50 of full priced goods, discounted to £32.50 with the Pick a Prize offer, and applied one of the Amex statement credits to get these for £22.50. Free click and collect. The statement credit showed immediately. Just tweak the full price spend according to your Pick a Prize discount to qualify for the £30 Amex offer.