I'll need to preen as much info out of you before, if I do do it
Sorry for the late reply, I've had a busy week.
I'll probably do it. The course is pretty simple. The swim might be difficult for you on a rough day, you will definitely want a calm day with the water. Lake is quite big, temperature was alright for me, but it can get choppy. I don't know what it is, but the deeper the water, the more uneasy I feel. I would try swimming in a big lake as preparation. There's something about swimming in deeper water, my body seems to react differently to it. As long as you keep our rhythm, focus and breathing, all will be good. You've done it all before, so you know what it's like, but I would definitely prepare for the deeper water. There are a row of large yellow boys, you swim along (the left?) of them, then turn left when you get to the last one and swim right toward the one in the middle, then just swim back along the other row. The choppiness or the sun could cause trouble sighting, but it is fairly simple.
The bike is a simple out and back, closed road. Pretty smooth as it's a popular A-road. No major climbs. A decent rider like yourself should be able to use the ups and downs to your advantage. There's nothing too steep there. I felt comfortable enough, but I wouldn't say I all out 'raced' it. There are marshals on motorbikes to check for drafting. At the briefing, the guy seemed pretty authoritative and strict, atmosphere is more race-like than event-like if that makes sense.
The run is along the pavement of the same road. You run along the road, then into a caravan site, up to the end of the site, and back the way you came. If you've read reviews in magazines, I think they over dramatize the climbing a little (although I believe the course used to go out on the A4212? Which would be more challenging). Be aware, before any sprint finish, they made us run a small loop of the transition car park before going through the inflatable arch.
You can take a look at the gradients on my Strava, it was 4th September. You will be a lot quicker than me on the bike. If you get a millpond on the lake you should be in good stead. Hopefully the course stays the same. I'll try and answer any questions you have as best I can.