How to correctly assign variables to confirmation url?

[Todor]

Hello,
I am currently creating a new payment module.
From validation.tpl I am redirecting to custom created demo.php
It is supposed to carry the ammount and the user data to a 3rd party credit card processing site.
The thing which I need is this:

Tools::redirectLink(__PS_BASE_URI__.'order-confirmation.php?key='.$customer->secure_key.'&id;_cart='.intval($cart->id).'&id;_module='.intval($Epay->id).'&id;_order='.intval($Epay->currentOrder))

This is from validation.php and sends the customer to the order condirmation page.
I need to get those variables in my demo.php
So far I have tried this:

$order_url =__PS_BASE_URI__.'order-confirmation.php?key='.$customer->secure_key.'&id;_cart='.intval($cart->id).'&id;_module='.$instance->id.'&id;_order='.intval($Epay->currentOrder);

and tried to initialize the variables but no luck.
also import of validation.php does not help?
Any ideas?