As a former Aviation English Language Assessor (no time these days) I would first check with your own state of licence issue (the country who holds your medical records) whether they will accept assessments from this company.
Knowing how strict the UK CAA is about the tests, I doubt very much that they will accept an automated on-line test. It was the strict policies put in place by the UK CAA and the costs associated with the approval that caused us to stop testing, and we were the first aviation training facility in the UK to be doing formal testing, back in 2009, well before any of the others started.
Things may have changed over the past couple of years - I do not know - but I would definitely check with my own CAA before spending any money.