Finding hidden form elements in selenium webdriver

Can somebody help me with the following, I would like to submit a form which contains several hidden elements. For example,

    <div id="42511f94-8a79-44b0-b875-caee5e4f8472" class="enquiry-modal-wrapper" style="height: 1964px;">
<div class="enquiry-modal-border-top main-contact ">
<div class="enquiry-modal-hold">
<div class="enquiry-modal">
<div class="enquiry-modal-header">
<div class="enquiry-modal-body">
<div id="8b492185-17f0-4343-b3b1-98c375943f07">
<form method="post" enctype="multipart/form-data" action="">
<input type="hidden" value="WVZ4z5ZYy0R1crDA84TnEiu51Y-N3-8fdP9gBthOPTZv2SYaOhISZixy_g0ZLKmXMt-e9_TiQoStwZUyFAFE0fsMTkg1" name="__RequestVerificationToken"/>
<input id="FormId" type="hidden" value="26ce85a6-4634-44f7-80bb-d9a391d9507f" name="FormId" data-val-required="The FormId field is required." data-val="true"/>
<input id="currentStep" type="hidden" value="1" name="currentStep"/>
<input type="hidden" value="31" name="CatSiteID"/>
<input id="target" type="hidden" value="InstructionID" name="target"/>
<div class="enquiry-modal-body-left">
<div class="enquiry-modal-body-right">
<div style="display:none">
<div class="enquiry-modal-body-bottom">
<input class="modal-btn" type="submit" value="Send Message"/>
<span class="contact-details" style="display: block;">
</div>
<input id="form_branchId" type="hidden" name="BranchID" value="1169"/>
<input id="form_instructionId" type="hidden" name="InstructionID" value="3844087"/>
</form>
</div>
</div>

If I use findElement(By.xpath()), I can find fields like name, email, and phone, and can pass data through sendKeys.but unable to find the button "Send Message" and click it.

Thanks in advance.