I got this deal via moneysavingexperts:
basically, if you sign up to this group voucher scheme here*, you can get a voucher to get a photobook for £8 instead of £30.
It seems to check out ok, and Martin Lewis is confident enough to recommend in his weekly email.
*NB, that is a personal referral link, so I will earn credit if you sign up via my link. PLease feel free to disregard that, and sign up via google if you prefer.