Thanks for the suggestions; I've got this resolved now and have a successful install. I don't think I did anything different this time, but I started from scratch again and repeated what I feel I had done before and it worked.
I could not remember seeing LDAP first time round so I specifically looked out for it this time, but didn't see it mentioned again. Still, it all installed now so not matter.
Now I've just got to do the conversion, but I think I'm going to have to speak nicely to Supanames (my host) to ask them to release a bit more resource as it just comes back with an error on the following web address:
I'll post a new topic for this though as it's outside the scope of the original post. Thanks again.