To answer your first question, most B-segment cars will feel pretty cramped for adults in the rear. You'd be better with a bigger family hatchback, although even these can be a little tight on space in the back. You could consider a Skoda Octavia - these have a huge amount of space. Have you considered a crossover SUV like the Peugeot 3008? These offer a lot more space.

In terms of reliability, it is usually Honda or Toyota models we recommend. A Hyundai i20 or i30 could be a good choice, too - they're generally very reliable and come with a generous five-year, unlimited mileage warranty. This might be of interest: www.honestjohn.co.uk/honest-john-satisfaction-inde.../