I ended up DIYing first time round as I had left it far too late for a tutor!
I was recommended the Susan Daughtrey books which we did over the summer and used her Practice papers too. I also bought another book by Nelson Thomas online. In the september I did the NFER papers with my DS.
I agree with the comments that it really brings you closer to your DC.
I also think that, for me, knowing what they struggle with meant that I could informally build it into everyday life, like games I spy on long journeys and adding up scores quickly when playing board games with the family.
If my DC wasn't wanting to do VR on Tues pm, for example, we just didn't bother and did it another time when they were more receptive.
I was very nervous about this first time but then after success and him passing the 11+ I decided to DIY with my DD too.
I guess I am lucky because I "get" VR which makes it easier and also both my DC were happy to do it with me (most of the time
I also think that learning to concentrate when normal family chaos is going on around them is a good thing!