using WordPress template tags outside of wordpress

Hello

i have my wordpress stored on my main directory and i want to create a page that has the wordpress template but i want to put my own information on it. I am puttin this page in my template file, here is the code i am using

<?php
   define('WP_USE_THEMES', false);
   require('https://www.mysite.co.uk/wp-blog-header.php');
   get_header();
?>
<div id="main">
<h1>Welcome to my site</h1>
</div>

<?php get_sidebar(); ?>
<?php get_footer(); ?>

it keeps giving me an error message saying
Fatal error: Call to undefined function get_header() in /home/user/public_html/wp-content/themes/site/mypage.php on line 4

any ideas on what im doing wrong?