I did mine a while back and as having had E as a later addition to my portfolio I felt it a helpful qualification. I decided to go that route as it was their core subject rather than a commercially driven addition as perhaps a NEBOSH Env was. The course notes and reading list were adequate and I wasn't concerned that I wouldn't have the breadth of the syllabus. I didn't feel a need to do further pre work to entry and this worked out ok.