.htaccess Problem

hello,

My problem is that im trying to make my login and checkout secure if i make the whole site secure i get insecure content,
Now all i want is login area secure and checkout secure.
Been search and everything i have tryed has failed im at a loss on it.
this is what i have in ht.access;

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

my website is puresupps.co.uk and ive tryed using the forced https pluging but that redirects me to puresupp.co.uk/index.php

and puresupp.co.uk is whats on my ssl cert.
any help appreciated.