If you look on the Stem Library (you will need to register and it is free) you will find the SMILE resources and the GAIM resources that have many practical activities.
Also I have found many of my students also enjoy the activities on the Transum site. One of the main points of the new GCSE is 'writing reasons' so it is important to help him see that being very detailed and systematic (I liken it to explaining everything to a martian as if the martian has no knowledge of maths at all) will help him prepare for his GCSE. I start this preparation with my students in yr 7 who are 11 yr olds. More praise for detail and systematic approaches than for solutions.
Hope this helps!