British brewing where yeasts are typically POF/- (Phenolic Off Flavour Negative). Where as Belgian and Germen top fermenting strains are often POF/+, and lower levels of these flavours are considered a characteristic rather than an fault.
Actually quite a lot of traditional British yeasts are POF+, although you wouldn't guess it looking at most homebrew catalogues - the Brewlab list gives you a better idea of the reality. In fact, a lot of the weird things that are typical of British brewing like Yorkshire squares can be viewed as an attempt to try and reduce the phenolics produced by their yeast. For an example, Lost & Grounded have actually sold commercial saisons made with WLP037 Yorkshire Square and by all accounts it is very clove-y if you treat it "normally" stuck in the bottom of a bucket, but is a lot less clovey if you try and replicate the high aeration of a typical square setup.
You can get a whiff of those phenolics in things like Harvey's and Sam Smiths, although I admit it's not strong even in fresh cask.
Blimey, the things I do in the name of science..... OK, I think I've identified the "unpleasant" flavour as clove, as described below...
First up, thanks
@chthon for your suggestions above. If you or anyone else has any further suggestions based on this then I'm open to your recommendations, perhaps for examples that are not heavy on the clove flavours......
Slightly weird sidenote - I really like German Hefeweizen whch is also renowned for having clove and/or banana flavours, but I've never had an issue with it. Perhaps the clove is just somehow much more pronounced in some Belgian beers???
Depends on your hefe - Benediktiner Weiss is an example of one that is really heavily clovey. But yeah, if you don't like clove then Belgian beers aren't really going to be your thing!
Can't argue with many of the recs above like Rochefort 10 (not 12!), Malheur 12 and just about anything from Dolle, De Ranke, De la Senne or Struise. De Ranke XX and Taras Boulba are interesting as Belgian takes on English bitter - not the same, but you can see the inspiration. If you see Dolle's Christmas beer, Stille Nacht, then snap it up, it's fab.
In terms of supermarkets, your best bets are probably Waitrose and Tesco. Waitrose usually has things like Tripel Karmaliet and the "ordinary" Boon kriek and geuze which are good introductions to the styles, and hopefully will inspire you to track down the next level up Mariage Parfait - the MP Kriek is utterly superb (but only available from specialists). One I don't think that's been mentioned so far is Delirium, which even small Tescos have, although I prefer their Guillotine which is much harder to fine here. Tesco sporadically has some of the Goose Island attempts at Belgian styles - Matilda is their take on Orval which I was underwhelmed by, Sofie their saison is much better IMO.
Somewhat randomly, Whole Foods has a pretty good selection of Belgian beers if you have one handy (there's a convenient one in the new development just off Piccadilly Circus) - they have a very USian idea of beer, which means Sam Smith, Belgium and lots of IPAs; at this time of year they have quite a few of the Belgian Xmas beers.
Also it's an obvious one, but the Belgo chain of restaurants is a convenient place to try the more mainstream Belgian beers like De Ranke - and then you have the hardcore places like Lowlander on Drury Lane which is amazing.