Lucy Tomas

This lightweight plugin will display a simple notification bar on the bottom of the page with a button to hide the notification.
<ul>
<li>Possible to add a ‘More Information’ button with a link on it. </li>
<li>All texts, colours and font size can be changed from a simple settings form.</li>
<li>Responsive.</li>
<li>Compatible with Polylang and WPML multilingual plugins</li>
</ul>

Simple Cookie Notification Bar

Displays a simple cookie notification bar on the bottom of the page, customizable colours and texts.

Herman

Adds a nice button on the page, by clicking on which pops up a window with your content. You can add the Shortcode of the contact form, Your company contact information, On Sale Products and else.
Features: 
– Choose icon (FontAwesome) and color for button 
– Add any content to popup bar using WordPress WYSIWYG editor 
– Supports any shortcode in content area 
– Choose on what post type show 
– Customize for specific post, page, product etc.
Enjoy!

FixBar – Fixed Bar

Adds a fixed block and the button to your site

Simple Cookie Notification Bar vs FixBar – Fixed Bar