Ah I see, my mistake. I haven’t noticed much in the way of coupons (admittedly I only pay attention to the US Blink store), usually just time-limited sales.
The only one I can think of is that they used to have a referral coupon system for current users to share with new customers, but I’m not sure if it’s still active (or if it ever applied to the UK).
Glad to hear you decided to take the plunge. Even without the sale price, IMHO the system is a pretty good deal for what it offers.