You'll be looking at a last-generation E-Class for that money. It's a good car but feels dated inside and has an old-fashioned infotainment system. Would a C-Class be big enough? You'd get the current model for £20k, which has a lovely interior. The Ford Mondeo isn't a bad choice, but we'd pick a Skoda Superb over the Mondeo. Also consider a Kia Optima SW.