You can check BA availability only on ba.com.

Or call Asiamiles to check.

As Asiamiles awards are mileage based... you can stretch your YYZ-LHR award to as far as Rome if you like.

I usually redeem an award YVR-LHR-CDG-CDG-LHR-YVR. For 60K miles. Or you may use the miles for one class upgrades on BA on almost any fare. However, it's World Traveller to World Traveller Plus... and WT+ to J, and J to F. You can't go from WT to J. One used to be able to... not any more..

Go to: http://www.asiamiles.com/en/redeem/flights/charts/#2

The mileage you see for each 'zone' is based on a oneway mileage. If you're travelling from YYZ-LHR-AMS return, you add the total mileage between YYZ-LHR-AMS. Then you look up the zone.