Another vote for Nantwich. It was my my first tri. Having done a few times now it would be the first one I would recommend to a beginner to do. But I've moved on now but will probably do it again in the future.
As above clubs vary a lot. When I originally enquired with the faster club in my town they did beginner runs of 6-7 miles !! I could do 4 miles. They were honest with me. I was recommend the othe running club and I joined them. Later I did join the other club as they actually train on my road so it was foolish not to. Both clubs have now changed anyway and positively recruit complete beginners.
Wouldn't prise me off my Orange for one As I said they are MTB's for roadies. I would say go for a well established brand line Spesh or Trek if insistent on having some roadie recognition.