Glasgow Celtic and their supporters would generally be the biggest shower of hypocrites going. I'm Irish but I despise the club. it is a British club so naturally the club want to remember the British war dead and contribute to the Legion etc. I hate seeing the Irish flag being waved prominently at such bigot riven occasion such as the Glasgow derby - the green white and orange meant to symbolise peace between the two communities.
But a lot of Glasgow Celtic fans come from Northern Ireland, leaving aside the hypocricy from the barstool republicans supporting a British club albeit with Irish roots, the British Army committed several attrocities there in the not too distant past. The Bloody Sunday antics by the British Army in Derry for example should shame any civilised nation. A Glasgow Celtic supporter Aiden McAnespie was also murdered passing through an armed crossing - they tend to sing about it a good bit. Where the money goes is also a bone of contention - subsidising drinks for the Lee Clegg's of this world is an argument I've heard many times.
Having lived in the UK for some time, my own view is that I personally wouldnt be buying any poppy. But I wouldnt dream of criticising the British club I support - Aston Villa - for doing so.