Hi darkstar_45,
I flew Canada 3000 from LGW-Toronto via Halifax in June 2000. The aircraft was an A330 (2-4-2 seating). THe aircraft was brand new having entered service the previous month.
Flight was good , a hot meal after takeoff and a snack before landing. A glass of wine withthe meal was free otherwise $4. Headphones were CAN$5 but you can keep them for the return flight.
Overhead screens for the movies rather than seat back tv's.
Flights were on time in both directions ( apart from Halifax- Toronto when we were delayed by over an hour due to the time it took to clear customs at Halifax (that obviously was not the airline's fault but due to two aircraft in front of us at Halifax- they are expanding their facilites)
Overall not as good as British Airways or probably Air Canada ( I have not flowen with AC for years) but then again the prices will be cheaper and overall it was good.
I think you can pre book seats for CAn$7 each way.
I do not konw what the A310 is like.
Hope this helps and have a great time