Hi @phil.owen
I think your code is caugin $other_page to be a true|false.
$other_page = is_page( '$current_user->user_login' );
Looks like that is a boolean returning function mate, perhaps you meant to write this?
$other_page = $current_user->user_login
if( is_page( $other_page ) )
{
the_field('favourite_movie', $other_page);
}
2 issues with your code:
1. quote marks in the is_page function
2. echo the_field does not need an echo