Aha! I realised that I did not have a php version attached to my domain. I have now changed this to version 5.5 and it seems to let me in. Many thanks for all of your help and super quick responses. Really appreciated!
Thanks for getting back to me so quickly!
I downloaded the plugin from the Etsy importer page attached to this support forum today so I assume it is the latest version. Before this I installed the plugin via the wordpress admin back end and ended up with the same problem.
I am running WordPress 4.2.1 which is where the error may have come from?
As far as I know I have all of the files which are included in the download from your plugin page.
