Have the endorsement throught the Ministry of Foreign Affairs in Canada and then you can contact the British Embassy in Doha. They have a stamp of the Canadian Embassy. Otherwise once arriving to Doha contact AMAREX. They can send the doc to the Canadian Embassy in Kuwait for attestation and then give it back to you. Please note that the Canadian Embassy will request you to send your passport or at least a Canadian ID plus some fees for the attestation. The all process takes around 1 week.
Hope this info will be usefull. Cheers