Anyway, I've found that they sell an artic. lorry, and a fuel tanker. They are a surprisingly close scale to 00, and I don't think they look out of place. If anything they're a tiny bit small, but I don't think it's noticeable.
Of course, they are Tesco 'liveried' and aren't packed with details, but they are very easy to customize. I'm painting a few extra details such as lights and registration plates, exhaust fumes etc. etc. This instantly makes them look much better. And the cab is detachable, if you just want that, or just the trailer.
And the best bit:
They're £1.30

Here are photos of the two I bought, with a man to show the scale:


They do sell cars too but they are definitely too big for 00.