Your training matrix will certainly get you there in 6 weeks, as long as you're comfortable with those distances (someone starting from scratch would need to start a little easier). You might want to add some extra distance to your swimming (I'd have a long swim day of 500m, for example) to account for open water (if your race is in open water) as sometimes you do end up swimming farther than the prescribed course, or it feels different.

And, it's a really good idea to combine intervals with regular swim/bike/run training. Instead of swimming 250m, swim a 50m warm up, 6x25 intervals with 10 seconds inbetween, 50m cool down. Or, 3x50m intervals. With running, run 30-60 second intervals after a good warm up. With cycling, try riding in harder gears for 1-2 minutes, then go back to your normal cadence. If anything, it helps add some variety.

Good luck! Sounds like you'll do great.