Sending an email with form variables to an email using wp_mail()

I have created a WP template and added to it a form. Below the form I have added the wp_mail() function to send the data the user has input to their email.

Now, I'm getting notices that:

Notice: Undefined index: name in mypath.

Any help how to resolve this would be most welcome.

Edit 1: to get the notice I had to remove the if statement.

Edit 2: this is literally all the code I have concerning the form. Am I missing something? Do I need to add add_action() somewhere or something like that?

The code:

<form id="form" method="post" action="">
    <label for="name">Name:</label>
    <input type="text" id="name" name="name">
    </br>
    <label for="surname">Surname:</label>
    <input type="text" id="surname" name="surname">
    </br>
    <label for="email">Email:</label>
    <input type="email" id="email" name="email">
    </br>
    <label for="tel">Phone number:</label> 
    <input type="tel" id="tel" name="tel">
    </br>
    <input type="submit" value="Submit" name="submit">
</form>

<?php
if(isset($_POST['submit'])) {
    $name = $_POST['name'];
    $surname = $_POST['surname'];
    $email = $_POST['email'];
    $tel = $_POST['tel'];
                    
    $to = $_POST[$email]; //sendto@example.com
    $subject = 'Reservation';
    $body = 'Name: ' . $name .  '\r\n' .
            'Surname: ' . $surname .  '\r\n' .
            'Email ' . $email .  '\r\n' .
            'Phone number: ' . $tel .  '\r\n';
                            
    wp_mail( $to, $subject, $body );
    echo "Sent!";
}
?>

The anwser

Edit 3: just to make it clear the solution was $to = $_POST['email']; //sendto@example.com so ['email'] not [$email].

The if statement is a sensible check - you don't want that code running until the $_POST variable has some values in it.

But, none of your form elements have names! eg this <input type="tel" id="tel"> should be <input type="tel" id="tel" name="tel">

Without that, you're not going to get very much.

PS Checkout PHP heredoc. That code at the end could be much more neatly written as:

    $body = <<< EOT
      Name: $name
      Surname: $surname
      Email: $email
      Phone number: $tel
    EOT;