hello and welcome to the site :thumbup:
there are a few things to check on the 2.2 engine, firstly listen to the engine when it's started from stone cold - any rattles which last longer than a second or two could mean the timing chain needs replacing, it's not expensive but a bargaining tool on the price. Also the exhaust manifold can crack, but they are only £100 new from the dealer - another bargaining tool.
otherwise it's a good engine and the astra a good car 8)