Wikipedia suggests prescription only in the UK. I think this is because it was banned as a food supplement in the 1990s, and only one medication got a licence, and that was a POM. Thus, any melatonin product is either an unlicensed medication (illegal) or prescription only.
The page you link to doesn't allow me to buy any product. Entering [melatonin] in their search box doesn't return any products containing melatonin.
The page you link to doesn't allow me to buy any product. Entering [melatonin] in their search box doesn't return any products containing melatonin.
(http://www.mhra.gov.uk/Howweregulate/Medicines/Licensingofme...)
"You can't buy melatonin over the counter in the UK" (http://www.webmd.boots.com/sleep-disorders/insomnia-in-adult...)
MHRA does regulate melatonin sales and prescriptions. Here are two examples:
UK website has prescription only melatonin, being advertised for off-label use (jet lag) and is told to stop (http://www.mhra.gov.uk/Howweregulate/Medicines/Advertisingof...) (Even though Cochrane found it's excellent for jetlag)
Also, unlicenced product (http://www.mhra.gov.uk/Howweregulate/Medicines/Advertisingof...)
EDIT: also, a web search for [buy codeine uk] returns many hits for offshore pharmacies selling into the UK.