The thing with pub food in the UK is knowing whether it's home made or not. You can be pretty certain that if you're getting a variety of 50 different types of dish for £3, then you haven't got a chef out the back preparing it from fresh. But pubs are suffering, and almost all of them need the additional revenue from food sales, so they get it in. And if their clientele want ready meals for £3, so be it.
However, there's also a question of appropriateness. I've had colleagues from overseas complain that the fish and chips they had in a pub wasn't particularly good. My initial reaction was to look at them slightly askance and wonder why on earth you'd go to a pub if you wanted fish and chips...
I do find the notion that good produce is unavailable to be utterly baffling. Maybe I'm lucky to live in an area with a tradition of market gardening, but I'd stick most of the veg we get up there with the best - and plenty of it as good as it gets (this season's asparagus has been superb).
However, I do agree that the incursion of big chains into the mid-level UK restaurant market has led to some fairly expensive, average food, particularly in London (a small, overcrowded, insular little corner of the country

)