I swam at the Lido today, where the triathlon is happening. I then went for a run around the actual route immediately after the swim. I can still move and even still stand up!! In fact, I feel surprisingly okay considering I did that! Timings weren't too bad either. I intentionally didn't push myself too hard on the swim so that I had energy to run (Though I missed the extra turns in the pool to push off from the wall - this pool is a 50m and I usually swim in a 25m). The hill at the beginning of the run didn't feel too steep. Most of the run is very slightly downhill which made it much easier than my training route!!
Swim 500m in 12m 28s then Run 1.4miles in16m53s.
Edit: I just checked the route and it would appear that I missed a bit of it out!! I didn't think it was far enough!