I cannot understand why if i am logged into the home page i have to again log into my mail page and viceversa it just bemuses me. And most home pages etc seem to be so complicated to use when trying to find something.
There isn't a direct 1:1 relationship between the two, and as such it would be impossible to do as you suggest. Each Plusnet account could have a large number of mailboxes associated with it, so there would't be an easy way to know which one to log you into. Likewise, you could have a mailbox set up for somebody who doesn't have permission to make changes to your account, thus being automatically logged into the PN account pages wouldn't be secure. I agree that the entire PN portal is a pain - I've been using it for a number of accounts since around 2005, and I still find it a pain