Can't export WordPress.org content

So I tried to export my blog but every time I try I’m getting this error:

No webpage was found for the web address: http://charleyward.co.uk/wp-admin/export.php?download=true&content=all&cat=0&post_author=0&post_start_date=0&post_end_date=0&post_status=0&page_author=0&page_start_date=0&page_end_date=0&page_status=0&submit=Download+Export+File

I found this thread which seems to apparently solve the problem: http://wordpress.org/support/topic/error-export-file?replies=6#post-1106903

However, unfortunately I’m not really literate with this kind of stuff; where would I find the php.ini file?

Or if anyone else can offer any different help that would be great, thanks.