The jeppy AT H 1/2 charts have a whole section on contingency procedures and RT phraseology. In addition to this our airline has a section of our OPS Manual pertaining to operation in the Tango routes.
Things like engine failure/depressurisation scenarios should be dealt with in your OPS manual as well as the QRH.
There is also a NATS manual which provides invaluable background information to how not only the Tango routes operate but the North Atlantic track system. It puts more "meat on the bones" of the information contained on the back of the jeppy charts. For example the background to strategic lateral offsetting etc.
Documents