To Danny Weed - it seems most posters on this thread are in the US, where cheap generic loperamide is much easier to find than in the UK. But the obvious MAJOR chemist chain does do a generic that's cheaper than Immodium, and it's uncontrolled/not difficult to import from the US.
I tapered down from a habit that had me on a 'stable' dose of 120-150mgs of oramorph/crushed MSTs, but often saw me take 2 to 3 times that for a buzz, or add on fentanyl patches, Oxys, hydro, DHC, whatever I could get my hands on. It only took about a month to taper off a six-month daily habit, and about a year of frequent use before that, but it sounds like you're experiencing worse withdrawals than I did: metabolisms vary. The three most useful tools, in my case, were loperamide, kratom and codeine when I jumped off of the morph. I tried to taper with a bunch of DHC continuous - but I find DHC almost as euphoric, in high doses, as hydro, and I couldn't control my intake.
It's not easy to source good kratom, but it really does, when found, take a lot of the edge off of withdrawals for many people - and if you're sensitive to such a relatively low dose of morphine, it might work for you. Not cheap though.
Otherwise, good luck, don't overdo the loperamide, and if it gets too rough, don't hesitate to seek medical attention - you can locate your local DDU and see if they're useful, if you don't want to 'fess up to your GP. But do NOT let them put you on even low-dose methadone: it's harder to kick than morph or H, from what I've seen (only used methadone twice, years ago, and although I was chipping H back then, it just made me high for an hour and then sick for 24, suspect I overdid it).
Final thing: I'd be very, very careful about turning to benzos. I was on 4-6mgs aprazolam a day during my heaviest opiate use, and kind of wish I'd tapered off the benzos before quitting the painkillers. I managed to switch to valium and get down to 25mgs a day: then had a panic attack when confronted with the object of a lifelong phobia, gulped 60mgs, and before I knew it, was on 100+ a day. I ran out of supplies, didn't get any intelligent responses from GPs, and am now tapering off of Etizolam: down to 5mgs a day, now, but it's getting tougher with each drop, and it's going to take at least a month or two to get down to zero. If you're not on benzos already, avoid if at all possible: the addiction/withdrawal cycle is much tougher on the body than opiates, can kill in extreme cases, and cold turkey's not an option, while tapering is a long, slow, and unpleasant process.
Promethazine will potentiate morphine, so be sparing in its use - it effectively increases the dose you're on.