I know when I lived in Italy you could buy transformers at hardware stores, I'm not sure if you can find them in the UK or not, though I'd expect so.
A plug adapter will not suffice. If you plug an American appliance expecting 120V into a British 240V mains socket, you'll probably destroy it. For a Royal 880, you'll probably want a 750W transformer. The largest motor shipped in the 880 was a 5.4A model (5.4A * 120V = 650W to two sig figs), though only the last ones made had that. Most are between 400 and 500 watts.
