Unprepared . . .

Work on your transitions. That's about the only thing you can improve with a week to go.

If you haven't before, an open water swim might help, just to have you experience the difference of swimming out of a pool.

You can also look around a bunch of threads that have some advice on what to bring and how to set up transition. As far as race time though, with a week to go training super hard won't do much for you and you risk injury.

Stay healthy, practice transitions, do some light training, and get some sleep.

Let the injury heal and forget the race. It's a super sprint and if you are going to compete, you risk further damage b/c you're going to be pushing yourself harder than you've trained for lately and (most likely) harder than your injury can take.

If you're not training as you desire, then it's going to be hard for you to judge how you will perform overall and if you can run with an injury. Take this time to get back in the pool and let the knee heal. Don't cause further knee damage just b/c you want to compete, it's just a race...there will be plenty more.

I am in a similar situation.   I am recovering from a second bout of achilles tendonitis.  I am going to 'race' but not worry about time or speed, just finish.  Like you I was a swimmer but it was decades ago.  Still very strong in the water though.  I am also getting pretty comfortable on a bike for a sprint distance.

Since I have not been able to train the way I would like this is how I plan to do my race.

Swim - focus on technique.  As a strong swimmer I will still post a respectable time.

Bike - the event where I will push myself. I have the most training in on the bike so I will listen to my body and do the best I can.

Run - will actually be a walk. I do not want to reinjure my achilles so I see no benefit in trying to save a few minutes here when I am not ready to run.  Too little benefit for the potential cost.

Have fun and go for the experience, not the clock.