That's a real shame, they're ubiquitous in Scotland; any brand's "70 shilling" will be in the 3.5% range. Belhaven Best is also extremely common, and that's 3.2%.
It's common in England for pubs to have at least one bitter that is below 4%.
They're awesome, too. Tonnes of flavour, huge variety, thoroughly drinkable, and low enough in alcohol that you can usually get an extra pint in. There are what the USians call microbreweries everywhere and any decent pub is likely to have a local session beer, frequently very good.
I live in Zürich now. The local lager's okay, but it's all lager, and it's all 5%, which is the upper limit of what I like. I miss good old fashioned ale.
I've not checked for "table beers" and don't know what that actually is. Goses aren't my style. IPAs are, and I've seen few if any session IPAs in person that hit at or below 4%. Just looking at the top 10 session IPAs that show up when I search for "session" on Untappd, I see only one below 4%, Even Keel at 3.8%. So I guess someone's making them, but no one's making them at 3 and almost no one is making them below 4.
Although honestly I don't think I'd want a session IPA at 4 or below. Most (though not all) session IPAs are pretty terrible at ~4.5. They'd probably taste like watery trash at 3.5.