Thank you for the recommendation. I've tried the test once and achieved 98 out of 100 which is encouraging!
I would comment that there are multiple spelling errors in the alternative answers, and in one it gave the correct answer as a word that does not occur in the English language: 'decussation' where the real meaning was 'cross-road intersection'.
On one occasion the website only gave the possibility of answering A, B, C or D but the answer was either true or false. I would have answered True if I had the opportunity which would have given me 99/100.
If you have further contact with any websites/apps to help prepare for the written test, please insist that the answers are checked by a native English speaker! I have yet to discover one which is not faulty in some way or another.