Doesn't fix any http content on secured pages

I’ve installed this plugin expecting it to fix the insecure files by changing their source from http://mydomain.co.uk to https://mydomain.co.uk but it hasn’t fixed any of them. My javascript & css files are all enqueued correctly & not hard-coded.
I only want the ssl certificate on account & checkout pages so I have selected Force SSL Exclusively which states that pages not secured via Force SSL or URL Filters will be redirected to HTTP. However I am able to go to https://www.mydomain.co.uk even though I have not selected the home page to be secured. The page is displayed with most of the css & javascript disabled due to being insecure (as described above? I thought that if I tried to go to https://www.mydomain.co.uk I should be redirected to http://www.mydomain.co.uk ?

http://wordpress.org/plugins/wordpress-https/