Like any perennial food plant, sweet chestnut trees have good and not so good years. And, frankly, most years in the UK are not so good. The imports from France, Italy, Corsica, etc are far superior.
Having said that, I spent loads of autumn Saturday afternoons crawling through the rhododendrons in Babworth Woods, or Lake Hill Wood, as a teenager, hunting down the chestnuts that had fallen from the trees. There’d be a few dads with kids around, chucking lumps of wood up at the trees trying to dislodge what was still on the branch (unripe), but we always came away with more.
I’m using the phrase ‘seasonal food’ to indicate those foods which, generally, are only available in their growing season, so many are wild and all grow in the UK.