Well you have lowering springs and standard shocks by the looks of it. That and 18" no wonder the ride is bad.
If you want to keep the lowering springs then I think at the very least you need uprated shocks as well. A set of Bilsteins or Konis will set you back well over £500, and even then it will still probably be hard. If that is too pricey a proposition I would simply put standard springs back in there, and possibly renew your OE shocks as well, they look fairly old and could be past it. For that your cheapest option may be to get KYB shocks and springs.
If you do either of the above and you still think the ride is too hard, then smaller wheels is the only other option.
To err is human, but you need an Alfa to really screw things up!
The road to heaven is paved with old Alfa's.