A simple and practical way to connect to the web version of WhatApp with your iPad is using the app “Messenger for WhatsApp”.
Just like the web version of WhatsApp, the "Messenger for WhatsApp" is an extension of your phone, which simply mirror your conversations and messages as they are in your phone device, that means, all your messages remain originally saved on your phone .
To connect, open the "Messenger for WhatsApp" and you will see a QR code, simply 'scan' this code using WhatsApp on your phone and you will be logged in. You will find this option within WhatsApp settings on your phone, at "WhatsApp Web" menu.
Your phone must be connected to the internet for the "WhatsApp Messenger is" to work, and in addition, make sure you have the latest version of WhatsApp is available for your phone.
This is not an official application of the company WhatsApp Inc. All features are loaded from the web version, published in http://web.whatsapp.com
To verify if your phone can sync with "Messenger for WhatsApp", try connect with your phone in http://web.whatsapp.com before buy this app.