I can get the coupon to display by using the below code - however what ever you type into the box it doesnt link up with box that is hidden which is where you have to put the code (if that makes sense)
<div class="cart-coupon">
<div class="table-responsive">
<table width="100%" height="auto" class="table table-none">
<tbody>
<tr>
<td class="text-right"><input type="text" name="coupon_code" class="form-control pull-right" value="<?php echo isset($coupon['code']) ? $coupon['code'] : ''; ?>" placeholder="<?php echo lang('text_apply_coupon'); ?>" /></td>
<td><a class="btn btn-default" onclick="applyCoupon();"><?php echo lang('button_apply_coupon'); ?></a></td>
</tr>
</tbody>
</table>
</div>
</div>