Im not in the UK ( wish I was- tee hee!) But I use methylcobalamin , the other, most common form is cyanocobalamin. Cyanocobolamin must be broken down to use, one of the components in it breaks down into is cyanide (minute amount). I prefer methylcobalamin because is more directly useful, if there's an absorption problem is would be easier to digest the methylcobalamin (this is what b12 shots are). Plus.. cyanide??? Who wants that??? This suplement is harder to fing. I had no luck at any of the healthfoods shops around here and had to order via the net. Google "methylcobalamin" and see what you find out. I hope this helps.