GoOutdoors are useless. Actually if you know exactly what you want and they have them, then it's ok (they do a decent range of La Sportiva for example), but don't bank on them for any advice, most members of staff there are students and teenagers.

Nothing really guaranteed to stick on wet rock. I note that the event you're doing is a triathlon.... if you intend to do further escapes into the fells, then I'd go for Mudclaws, La Sportiva Mutants, or my personal fave, VJ Irocks. You're going up Fairfield via Nab Scar...? Any of these would be more than suitable.

But if you preference is usually more standard "off road running" then you might be better with something that you can use on more trailly surfaces as well, something like La Sportiva Bushido (great shoe, not much cushioning) or another fave of mine, La Sportiva Ultra Raptor (lots more cushioning, built more like a normal trainer, plenty of grip, but wouldn't wear in a pure Fell Race).