Hi,
Thanks for your reply – it turns out it was a problem with a conflicting plugin and once that was disabled it sorted itself out.
The website has now been live for a week and seems to be working ok, however, I have just logged in to check some settings – have gone to the customise page, at which point I get a HTTP 500 error as well. I am also getting this error on my localserver development test site.
Nothing has changed on the website in the past week to cause this – I haven’t even logged in! Could you please help me?