The 1.8 is a K series. My customer bought one was quite delighted with it. The first thing I thought was he has been had. A few weeks later he was faced with a £2k bill for a new engine because the head gasket had gone and the head had already being skimmed so it could not be reskimmed.
The Ford Ka is quite a good buy but I would have thought a used Panda would make more sense because they don't rust.
Ok I can't be bothered to go and check on Autotrader but I would think you'd get a better spec, Astra or similar for less money than a Ka, for that matter my last Vectra CDX cost about the same as a similar vintage Ka - but then the Vectra is hardly popular with learner drivers.
This daft list specifically mentions the 1.8 turbo, probably the worst possible choice for reliability; maybe whoever wrote the list hasn't worked out why they're so cheap.