No prob, figured it may be one of those, some of them are the most widely distributed.
Chimay is far and away the most widely distributed and consumed of the trappist ales. You should easily be able to find it in the UK. If you like it, try similar beers from Rochefort (10 or 8), Westmalle, Achel, la Trappe, and Koenigshaven. If you ever make it back to belgium, Westvleteren 12 (or any of their other beers) are a must try, but are only sold at the monastery. These are all trappist abbey ales similar to chimay. There are a lot of other great belgian quads out there that are not trappist made ales as well.
Kriek is still made and widely available, and it is actually infused with cherries. It is typically a very sour lambic made by many different belgian (and now american) brewers. Usually made with wild yeast and spontaneously fermented, then barrel aged with cherries. Some examples that may be easier examples to find today are Cantillon Kriek, Boon Oude Kriek and Marriage Parfait Kriek, Oud Beersel Oude Kriek, New Belgium Brewing Krieks (they make a few), 3 fonteinen kriek, Hanssen's Oude Kriek, or Lindeman's Cuvee Renee Kriek (NOT the usual Lindemans, which call themselves lambic, but are really much more like fruit beer [a style of its own that is not sour])
There are other sour lambics made with all types of fruit though (raspberries, blueberries, currants, peach, etc.) so the one you had may well have had raspberries, it just probably wouldn't carry the "kriek" on the label, which is typically on used when morello cherries are utilized. All of these sour lambics age beautifully, for decades, but sour beers are an acquired taste for many.
If the one you remember was not sour, and only "tart" it was likely Lindeman's "regular" Kriek, which is more like a sweet fruit beer and can be found everywhere along with their Cassis, Peach, Apple and other varieties. My wife loves them mixed 50/50 with champagne, hahaha.
We get many brewdog offerings here, but I have not seen Elvis Juice. I'll keep an eye out for it. I like many of their beers, others I am not a huge fan of. They are well known for making some of the most high abv beers on the planet though, some pushing 55% abv and some sold inside stuffed squirrels (not kidding). A crazy brewery.
If you are a beer fan, or interested in craft beer, i'd recommend checking out beeradvocate.com. You can find information on almost any beer on the planet, as well as reviews. They have forums similar to this one as well where one can get recommendations, discuss beers and their availability/merits. etc. It can be a rabbit hole like this forum, or just an easy resource for getting beer ratings and reviews.