I normally use photonic (photonic and Snapfish do some great offers time to time) I've also used Snapfish and a few others, boots is definitely the worst. The colours are not as vibrant and the images are not as sharp. Many of the the others do free prints and only pay shipping, I would recommend giving them a go.
Can confirm 99p delivered. Codes stacked. 25 free prints when you sign up plus 1p / print. Free delivery code wasn't accepted, unfortunately. :(
Are these their standard photos? Can't say I've had any issues really. As long as you use high quality pictures to begin with then they turn out fine. Use low quality photos and they turn out crap.
99p delivered! Ha
Are you adding the promo code correctly?