Magento 2 Cache – Disable Cache for Specific Section or Block

You can try

    <reference name="needed block">
        <action method="setCacheLifetime"><s>null</s></action>
    </reference>

or

    <reference name="needed block">
        <action method="setCacheLifetime" />
    </reference>

to set it to null.

But probably it is better to use ajax.

There is a good article about null or 0 meaning http://blog.kyp.fr/make-a-clean-sweep-of-commons-magento-cache_lifetime-workarounds-usage-in-cache-block-policy/ ^{(link is broken)}

You have already found your solution. You are just a few steps off. The answer is indeed the same as: https://stackoverflow.com/questions/8405232/disable-bypass-magento-full-page-cache-on-single-page.

You need to see if the action is an instance of the CMS controller. Then you need to check to see if the page being requested is the one you want to not cache.

1-create the module

2- insert xml in config.xml

3- insert the function in your observer

public function processPreDispatch(Varien_Event_Observer $observer)
{
    $action = $observer->getEvent()->getControllerAction();

    // Check to see if $action is a Product controller
    if ($action instanceof Mage_Cms_PageController) {

        $cache = Mage::app()->getCacheInstance();

        // Tell Magento to 'ban' the use of FPC for this request
        $cache->banUse('full_page');
    }
}