I get about 20,000 miles, or 12 months, out of my tyres. Mid range American thingies. Hard to make the front wheels let go on an auto.
Not that I'd want to, of course.
The Astras don't do many miles , Mrs Builder drives like she stole it and gets similar wear to you , 20000 miles over 3 years
she's got Goodyear Vector 4 season gen 3 (about £80 a corner)
I'm not doing burn-outs or driving like a mentalist
my rear tyres don't last
(Hunter hawkeye checked not long ago, so it's not alignment issues)
I've tried all sorts of tyres too ,Pirelli P7, goodyear efficient grip ,Avon zv7,roadstone eurovis sport, DAVANTI DX390
so i'm NOT buying Goodyear Vector 4 season gen 3 for mine at £170 per corner