Centrica Online Tests



I would like to ask anyone who has done the online tests for Centrica the following questions.

How were the tests?

What advice do you have to prepare for the tests?

Also, the link for additional practice questions has verbal and numerical practice test questions and advice for completing personality questionnaires and SJTs.
I would like to ask if the online assessment for Centrica contains all 4 of these tests (i.e., verbal, numerical, personality questionnaire and SJT)?
If not which tests does it contain?

I would also like to ask if we can chose the order of which test to do first and which test to do afterwards or is there a fixed order which test has to be done first followed by which next test i.e is it the case that we are first required to do numerical then verbal and then personality questionnaire?