Can't log into the forum on your iPhone?

[*]Launch the Settings app from the Home screen of your iPhone or iPad.
[*]Scroll down and tap on Safari.
[*]Now scroll all the way to the bottom and tap on Advanced.
[*]Tap on Website Data. ... 
[*]Scroll to the bottom again and tap on Remove All Website Data.
[*]Confirm one more time you'd like to delete all data.

Good lad!

But this will delete all data from inside Safari though and not just related to Nuts no?

You can simply download another web browser instead which gets round the issue as well such as Chrome Browser.

I may not want to lose my cookies etc for other sites...

This solves the problem,Most people wouldn't want to keep flicking through different browsers to access certain sites.