Can I trial essentials plus before I buy it?

Sure, you can try out all the software versions, including Essentials+, on the Demo page at https://www.ultimatewb.com/demolinks .  There are links there for the software admin panel, and the frontend (resulting website).

You can compare the 3 software versions on the Compare page here: https://www.ultimatewb.com/compare-uwb  .