Repairable... Yes.
Worth it... That’s up to you.
Take all of this with a pinch of salt, as I’m no expert in body repair or the costs.
TBH I think your best play is to go out and get some quotes, I believe lot of body places do free estimates.
It’s certainly a write off I’d imagine. I smashed my driver’s side rear door a couple of years back, but didn’t go through the insurance as I knew they’d write it off (even with it being a relatively easy repair, it’s still only an old 500 quid astra in their eyes).
It’s hard to tell properly just by looking at the pics, but you might be lucky in that the impact may of just kinked the outer skin of the rear quarter forwards onto the door, and the door/frame itself is ok. But there’s a potential for damage to the inner panels behind it.
Getting hold of the parts second hand to save money shouldn’t be too difficult if you can find a decent scrap car to get them off. The problem though is not the price of the parts, it’s the labour for welding/prepping/painting that really screws you deep.
For example, you could get all the parts brand new for, lets say £600, but the time and labour for a bodyshop to cut the old panels off, potentially repair any damage underneath them, straighten brackets/hinges, align and weld the new panels on, filler, prep, then finally paint. You could end up spending, say 3k+ on it.
At the end of the day, as most people would tell you, it all depends on wether you’re willing to spend that sort of money on an old Astra.
But like I said, get some quotes and go from there. It may be a lot cheaper then I’m making out.