I think you may be even worse than me at swimming! :)
At Goodwin in about 1985 I used to blast 800m in sub-24, pb was (I think) about 21:55. (breast stroke tho)
These days I still go at the same pace but need a rest 3 or 4 times per session (managed 1km this week).
No risk of doing a triathlon!
I would be very surprised if i was a better swimmer than you. I'm rubbish. Can't remember the last time I went swimming.
What made you decide to go?
Nothing better to do on a Friday night. Sad I know but the rest of the family were going so I thought I may as well join them.