Also thinking of selling my Giulietta. I love the car, but there are some niggles that annoy me that I find hard to get over. It wasn't as big of a jump from our MiTo (which is staying!) that I thought it would be. I'm finding it extremely hard to find a car that I would want in the same price range / class though. Everything with the same power, style, comfort, mileage and price is much, much more expensive than what we got the Giulietta for (thank you AR depreciation, I guess :P). But then I look at it and I realize that it's going to be hard to part with it.
I secretly very much covet the 3rd gen Lexus GS450H as a commute cruiser. I've found that I really crave having a quiet and comfortable car when I'm not driving for fun. The MiTo is fun to toss in the corners, but less so on commutes/longer trips. The Giulietta, unfortunately, isn't as quiet as I was hoping. It should be noted that Swedish asphalt is very coarce, and most cars that would fare well in Europe get very high NVH here.
£20k would probably land you a nice 4th gen Lexus GS, he he. Plenty of power and decent mileage. The family could cruise in comfort.