The eleven plus website has lots of useful information, particularly on the details of what school does what test. Be aware schools may be swapping to the CEM tests which are supposedly untutorable (Yeh, right). There is no certainty that any child will pass or fail, but the more they prepare for that specific test, the better chance they will stand.
Dd did 3 tests, so there is nothing to stop them doing more than one, then making your mind up on which school once you have the results. Look up alternate days for the tests if there are clashes.
Dd had good levels for maths, but we had a tutor for English for about 3 months, as I felt I was not capable of teaching her this. The NVR and VR we did at home, just doing a few tests here and there through year 4 then building up from about April of year 5. I thought, from reading the 11 plus forum, we had left it too late, but she was fine. Her speed really picked up over the last few weeks.
I came to the conclusion that the 11+ test is not a level playing field and the children who are prepared to put the work in over the summer holidays are the children who deserve to get in.
I would say over year 4 concentrate on maths because it is their lowest score and learning maths is never wasted. Do an NVR and VR test "Just for fun" and see how they go. (Pick easier levels to build up their confidence).