BT codes don't come round often nor they do many great deals but just got an email for 20% on their Philips Hue range. I got a bulk of bulbs with Argos home25 discount but they have since take the smart lightings range of their Home list so this may be useful for some.
Works great with Alexa which I think Maplin might be selling with £20 off or something at the moment?
Code I got on email is HUE201004. Hope this works for you.