Of First Thoughts on a First Triathlon

I'm contemplating doing a triathlon at the moment. That's a swim and a bike ride followed by a run. It's the swim bit that bothers me most for I've never been a quick swimmer and I'm easily bored too!
The first (and indeed last) time I ran a marathon was when I was 17. I managed it in under four hours which was quite respectable I thought. I was caught taking the lift to the first floor at college the following morning however, so I must have been in a pretty bad state.
On Monday of this week I swam 40 lengths of the local pool. Later that evening I cycled 15 miles. The run leg I have still to do! What bothers me is that on the day of the race transition takes just a few seconds and not days which I'm allowing myself to at the moment. I wonder if the organisers would allow me at least a sit down and have a cup of tea before the next bit! I could always ask!