Your car shouldn't take 30 seconds of turning over to start.
There was an old rule that it took six minutes of driving to replace every second the car turned over.
I think you're being too harsh on the battery, particularly as you've got this thread going:https://www.wikiwirral.co.uk/forums/ubbthreads.php/topics/869050/Vauxhall_Zafira_2007.html
How old is your battery? They only have a usable lifespan of around five years. Measuring the voltage after being stood overnight is well worth doing.
Batteries are funny things and can do funny things to a car's electrical system. My brother did a diagnostic on a car a couple of weeks ago, the electrics were going haywire, but the car seemed to start OK. The battery was 9 years old (was on it since new) and showing 8V when stood! The owner thought that just because it started the car it was fine!