Hi Grahame,
Don't be put off by the bad reviews of Small Planet. We've just come back from a holiday with Olympic to Sivota in Northern Greece, and flew to Preveza with Small Planet from Manchester. The crew were helpful without being over-friendly, the service was fine and the planes comfortable. The upholstery in the plane going out was in better nick than in the one coming back, and the landing in Manchester was a little bit wobbly, but otherwise no problem. On time both ways and we left from, and arrived in, the right airport!
Having said that, Preveza does not really compare to the chaos of Heraklion. There were three flights out on the day we left - for the whole day! But Manchester and Gatwick might be fairly comparable.
Arnaki