If you want to do ‘anti-terrorism’ in a domestic context, you realistically have three options that I can think of:
1. Joint Task Force 2 with CAF. In a hypothetical situation where a domestic attack exceeds the capabilities of law enforcement, JTF would be cleanup in aisle 3. But outside of for real ops they will train for a lot of domestic antiterrorism stuff. Offhand I’m not aware of a domestic terrorism situation ever actually getting to the point where JTF2 resolved the situation, but conceivably it could have happened. I know they have been involved in real situations that came short of JTF2 ending it kinetically.
2. Join the RCMP and get into one of their Integrated National Security Enforcement Teams. They have the legal mandate to actually investigate and lay charges for terrorism offences, and they’re pretty busy.
3. Join CSIS and investigate threats to the security of Canada on the intelligence side.
None of these are easy or quick paths. All would likely be quite rewarding in their own right. Either the reserves or the reg force can be a stepping stone to all three. I’ve left out some more niche options like, for instance, the Ontario Provincial Police Provincial Anti-Terrorism Section; maybe the Sureté de Quebec have something similar. Any actual terrorism arrests would probably be a RCMP Emergency Response Team. But those three are the ones where you can reach and then do a whole career with an anti-terrorism focus. Without knowing anything more about your background that’s all I can offer. I’ll let others speak to the relationship side of a CAF career.