* Hochschulreife: This is the most common and generally accepted translation. It literally means "university maturity" and refers to the qualification that allows someone to attend university.
* Abitur: This refers specifically to the German university entrance qualification. While not a direct equivalent, it's often the closest comparison and understood in that context.
* (Britisches) Abitur: If you want to be absolutely clear you're referring to the British A-levels, you could specify "British Abitur," though it's a bit clunky.
Therefore, Hochschulreife is usually the best option unless you need to emphasize the British origin.