I own the domain thomas-smyth.co.uk, so I have tried the following piece of code to redirect the user.
window.location.href = "http://thomas-smyth.co.uk/home.php";
You have posted the wrong code. In your Js File thomas-smyth.co.uk/functions/login.js on your webserver is this:
//Re-directs to subdomain. window.location.href = "http://www.thomas.smyth.co.uk/home.php";
this should be fixed to
//Re-directs to subdomain. window.location.href = "http://thomas-smyth.co.uk/home.php";
@vlaz mentioned right, you have a second mistake with a wrong dot instead of a dash
And btw you should explain your problem a bit more. More code would be usefull next time if you want some help.