When you run the checkout wizard it should create all the pages that are necessary for your gateway. You will only have the credit cards fields on the checkout page if you are using a local checkout. If you are using a remote checkout option then you will not have these fields available on the checkout page.
To get the users to go to the https version of the page you can just link to it with the full absolute web path like this:
instead of going to checkout.php you should go to
There is not a prebuilt select list for UK counties, it might be a good idea to just make this a text type input and allow the user to enter their own.