Not the best person to give advise but I can share what we are doing.
We Revise everything learned really ... At the moment, interpreting pie charts with DS, doing additions, solving word problems, division and multiplication & some algebra.
According to my friend (whose DS is now a pupil the school) SGS setting very challenging Maths test papers every year & past English test papers included creative writing & non-fiction tasks.
During the week I am setting short tasks for DS such as writing formal/informal letter, in Weekends- newspaper articles, or 30 minutes essays-i.e descriptive writing if he doesn't have something similar for his Literacy homework of course.
Not sure why but DS's spelling getting worse so doing short sessions of SPaG straight after returning from school.
With only 135 places up for grabs, the boys must be extremely well prepared...no room for errors