You can get a normal Suica just about anywhere.

Little over a decade ago I did exactly the same. I ended up buying a Suica card at Ueno station from a clerk, which was a bit of an adventure since she was eager to help but barely spoke any English and I barely spoke any Japanese. Together we skillfully massacred both languages with an ad-hoc pidgin and lots of gesturing. Due to an issue with my wireless hotspot I only had an old school phrasebook at my disposal, which was about as helpful as the infamous Monty Python sketch implies. The airport seemed much more convenient as a tourist since everyone there at the very least spoke basic English. At the time it was certainly possible to get a Suica card at a major train station, though admittedly not easy.

While we got ours at the Osaka airport (KIX), I am sure I saw the "purchase a new SUICA/ICOCA" options at a few terminals while topping up. I suppose you mixed up the "Welcome to SUICA" tourist card (available at fewer locations) with the normal one? I was under the impression there was a lot of confusing information floating around online.

But I agree, public transport in London is - as a tourist - more straight forward. Just a matter of spotting the terminals at some stations IIRC. OTOH in Japan we found no station with an elevator smelling like someone used a hippie bus as an emergency toilet ;-)