I did the Oly distance last year which was on the same day as Grafman. Its a lake swim with a beach start, its 2 laps and you have to run out of the water round a cone and back in. The ride is relatively flat with only a couple of short sharp hills but nothing to worry about. the main problem on the bike is that it is quite exposed so wind can be a nightmare. The run in on tarmac, gravel and trails round the lake so again pretty flat with a couple of short sharp hills, not bad underfoot so normal road shoes should be fine.
I've done a few events organised by this company and always found them very good, should be a fun day.
I'm sure someone else asked about Grafman so my be another pirate or 2 about. Iron Scribe also did the HIM last year.
Hows your training going Cheggers?
I'll be doing it but not in the best shape as I lost about 3 weeks training a chest infection.