The A318 can comfortably fly from London to New York non-stop. The issue is the runway at LCY, which is too short to allow a fully laden A318 to take off.
A quick check of the estimated performances of the new C-Series shows that even when filled to the brim with fuel, it would be able to safely take off from LCY’s short runway.
However, with an estimated range of only 2950nm, the aircraft would struggle to safely fly the over 3000nm to New York (especially if it encountered poor weather over the Atlantic, or was forced to hold over JFK for any amount of time).
Seems unlikely that Odyssey Airlines will have much success, unless Bombardier launch an extended range version of their C-Series.