Thanks for your reply!
I did change the site URL first. Then I copied the .htaccess file to the root directory. I was going to search and destroy but didn’t get that far before it died.
I then tried to restore from my backup and the old site on the root is working again but my wordpress on the sub-directory has not restored properly and now looks like this: http://www.stateofplayarts.co.uk/core
I guess I need to get it back to how it was before trying the process again.
Thanks
Dan