All the Energy Certificate will do is give a rating to your property so potential buyers can see how energy efficient it is (that's the theory anyway).
You dont have to do anything, buy anything more, or take any advice they give. You'll probably be told something along the lines that if you install solar panels on your roof at a cost of �25,000 you can possibly save �1 a week on your gas or electricity bill, or some such thing.
Dont worry about it, very few people look at the energy certificate anyway.