How do I Unlock British Subs?

I'm fairly new here, I've got 100 hours played but that's over the course of many years, I play very sparingly. I'm wondering how I'm supposed to use these British tokens to unlock these British subs, something about Sequential Bundles but I've gone through every menu and can't seem find these Bundles. Says 12.1 we're on 12.1 so I'm really lost here. Thanks!