First waste should be recycled in The u.k
At the risk of being boring, in the first instance waste should, of course, be avoided. Reduce, reuse, recycle, with recycle being a distant third (or wherever it occurs in expanded versions of this list, as there are quite a few more 'r's to be added to it in various ways).
It's really annoying that recycling has become the assumed most important thing to do. I always suspect that must be because the word is more eye-catching and because making things disappear into the great blue recycling yonder seems so much easier than not generating waste in the first place.
There is obviously a lot of plastic waste in the oceans that dates back decades, but could the attempt to increase recycling rates instead of incinerating waste also be partly responsible for the huge amount of plastic rubbish around? In Germany, this started with the 'yellow sacks' 'recycling' regime introduced in the early 90s, when a much better law that would have reduced waste at source was scuppered. Soon afterwards, 'yellow sacks' were discovered dumped all over Europe and I wouldn't be surprised if much of this stuff also found its way into the sea. It also seems likely that 'recycling' from Britain would have gone the same way.