While we're noting, they are pretty good about telling you/charging you less if it's something that's available off prescription (and was prescribed just to record the advice, or particularly because non-standard dosage advised, etc.) so £12 too much.
Like paracetamol say, you'd need a pretty hefty prescription to be able to buy enough all at once that £12 was a good deal. (A standard box is I think 24x500mg, good for three days (4h spacing, but 4x1g max is advised, not 6x) at max standard dosage, can buy two off the shelf for about £1, so you'd need a prescription for almost three months' worth, or a correspondingly higher dose...)
Also, £12 is the one-off price, there are better subscription type rates for people with medium/long-term recurring prescriptions.
Like paracetamol say, you'd need a pretty hefty prescription to be able to buy enough all at once that £12 was a good deal. (A standard box is I think 24x500mg, good for three days (4h spacing, but 4x1g max is advised, not 6x) at max standard dosage, can buy two off the shelf for about £1, so you'd need a prescription for almost three months' worth, or a correspondingly higher dose...)
Also, £12 is the one-off price, there are better subscription type rates for people with medium/long-term recurring prescriptions.