hiya, first of all, I respect your perspective. but just wanted to mention a few things and we may have to agree to disagree. the poppy is a symbol of the fallen soldiers in WW1, not WW2. you can check out the Royal Legion website, which describes it in more detail.
I think wars are often romanticised by countries... perhaps as a way of dealing with the trauma? WWI was a result of the heavy handed response of the Allies to a not very significant assassination and really was an excuse to "put Germany in it's place" as the Allies were threatened by its rapid rise following the unification of Germany in the late 1800s. Remember European nations have always fought each other, this was just a new excuse. sadly due to advances in technology, it led to huge numbers dying... mainly young men from lower socio-economic classes.
WW2 was a direct result of too harsh reparations imposed on Germany by the Allies. this allowed Hitler to come to power. To romanticise the above history and simplify it so we can be "proud of winning the world wars" is not very accurate in my mind. the Allies also committed some war crimes eg. Russians carrying out total destruction and mass rape in certain German cities following the war and not to forget Hiroshima and Nagasaki. in war, both sides ultimately lose. the best war is the one not fought.
Afghanistan as a use of legitimate force? the only people that were harmed were civilians. millions of children died. not to mention the taliban were put in place by the Americans during the cold War to push back the Russians and Osama bin Laden was following Wahabism which was instituted in Saudi Arabia by the British in order to push out the Ottomans in the early 1900s. the taliban are back in Afghanistan, no worse off for the war. the women are just as oppressed. and now, the whole country is much worse off. they were just about surviving before the war. if you really think its a legitimate use of force, I recommend perhaps to do some reading (not mass media) on the impact of war in Afghanistan and neocolonialism. In terms of the terrorism... if anything it made things worse! Britain only suffered terrorist attacks the war started, not before. the war gave fresh fodder to terrorist recruiters. and together with the Iraq war, it led to the formation of ISIS.
let's not forget that largest group of victims of this sort of terrorism are Muslims. the taliban are killing Muslims. isis is killing Muslims. attacking those who are already facing all of this can only make things worse. and also let's not forget that the armies who have had real success against these terrorist groups such as the SDF and the Turkish army are locally based. fighting a complex war, on an unknown and difficult terrain by heavy handed tactics by a foreign army trained to fight in northern europe was never going to work. and finally it was a colossal waste of money. if only that money was given to the NHS, think of how many would have benefitted.
tbh Muslims in this country have always joined the army. but after these two wars, it will take a long time before most Muslims will consider the army as a career. I have to point out that Muslims have very severe restrictions as to when they are permitted to go to war and are absolutely forbidden to kill any civilians, to destroy any crops/property. so this restricts truly practising Muslims from joining the army (in pretty much any country in the modern day).
the lack of Muslims in the police force is more due to widespread racism as we are aware. also certain cultures/ethnicities push their children towards more academic professions eg medicine which might also be a factor.
sorry I couldn't provide you with any solutions.