Wish I had seen this topic when it was more active!
I'm not in the UK atm but when I was there I definitely missed Mexican food...esp since we had the BEST mexican the month before in Atlanta!
I also missed coffee..I wasnt a huge coffee drinker (I love it just didnt drink it every single day before) but when I went over I HAD to have it, and filtered coffee is apparently American

So I had to buy a cafetiere..it took awhile to get the hang of it, and now I almost miss that way of making it
The biggest thing was tomato sauce...I bought passata from Tesco...it was horrible the first time around, but he was a dear and ate it anyway (how I dont know

). I got the hang of it soon (kinda had to I make LOTS of pasta

).
However I did find new foods I loved over there...Hob Nobs..mmmmmmm (White chocolate digestives too...my dbf wondered where they all went hehe) .

Ah yes and odd as they sound cauliflower cheese grills...potato waffles...yum! (I know I went a bit off track there hehe)
And there were some things that I can get in the US but were just different, such as tuna in sunflower oil, I prefer it that way, but it is soo expensive here in the US!!
My son is going with me this trip and he loves pickles, baby dills to be exact, I couldnt find any in the UK...care package! hehe
But overall there was so much new stuff to try that I dont think I'd miss much from here.