Astra H +8500€ for compact combo?

Hello, I’m looking for a young used car again. Old car: At the moment I drive a Opel Astra H (EZ: 05/2004 1.4 with 90hp) I bought this one at the end of 2011 (8500€) because he had 30k Km on the clock. Now he has almost 95k Km. Inspections and oil changes were made regularly. Unfortunately, the automatic air conditioning only warms up if you put it on high otherwise the car is in good condition and 8x matured (steel rims). What can I do when I exchange or sell for him? n get? 250€? New car: So now to my wishes. Budget is about 850€ + what the Astra brings! Since I am not too much on the road it should become a gasoline. It is important to me a similar large rear opening as with the Astra H so that you can throw in a mountain bike without any problems. Also should have a USB port or AUX. I imagined a compact car like the Ford Focus tournament MK3, Kia ceed sw (second Gen.), Seat Leon II (Bj um 2011) or Skoda Octavia (Bj from 2010). Do you get reasonable used ones for my budget of which I imagined? Which variants are flaws vulnerable and where should you leave your fingers off? Are there other interesting used ones in size that are reliable? Thank you very much Kai