Yooky, I have just gone through this with my DS.
First know your child’s ability, if they are generally working well then either tutor yourself or get a tutor.
My son had a tutor twice a week for seven weeks starting from October - really for maths and NVR, I couldn’t do it. Tutor gave no homework, which worked for him and me! Tutor was for an hour each session, which I thought was enough.
He was able to cope but tbh I wished I started a couple of months earlier. I also did verbal reasoning with him too. That was via the Bond book.
You also have to know when to back off and let them have fun. We did nothing on the weekends apart from going out, sport and reading. And a lot of PS4 when no tutoring.
Do lots of past papers from the indies you want to go to. It’s possible, but if you can do a little bit over the summer please do. It’s also about getting your child to work quickly and accurately under exam conditions, so you will have to do some work over Xmas.
He went for two indies and got both. So I wish you the best of luck. Yes, it can be done especially if your child wants to go to the school and they understand they need to be at a certain level in order to be in with a chance!
I work flexibly and believe it helped him as I could support him at home when needed. So, if you can be there and it works for you - go for it!