Hi Crazy I don't know whether Robin will be able to help you, but I think he'll give you a reasonable idea of whether he feels he can or can't. I was impressed with his straight talking and would def recommend visiting him. It's the main reason I wanted our DS to see him, rather than just starting with the book - I was worried that the TH wouldn't work for him and needed to start with an assessment.
Here's some of my thoughts and experiences. DS is 4, so not sure how much will be the same for you with an older boy, but I was so surprised with DS and what he can / will do - I underestimated him!
I was worried about how easy we would find it to do at home - DS is 4 and wilful! He was becoming very bossy and getting stuck in his ways - fussy about food, difficult to manage, angry and always doing the opposite of what we wanted. Robin made a real impact on him, plus we talked quite a bit about brain food and food that could help with things at pre-school etc. The food wasn't difficult at all - he quickly cottoned onto the menu idea and kept asking what was on the list for lunch etc. He thinks that Robin tells us what to eat. 
He helps cook lots of things, which is especially good with new food and, just as Robin said, the more he gets into the programme, the more open he is to new things. DD aged 2 is not as easy, but I am hoping that she will get there.
The exercises are good fun and we do them all together - not so much now, but at the beginning. DH came to the appointment too and DS loved doing the same exercises as him.
The supplements are ok too - the fish oils are chewable and taste of orange. I dole them out for good behaviour too and we call them fishy sweets. The other supplements are ok to drink. I tried him on probiotics but he isn't keen on swallowing tablets - the only way he will have them is if they are broken up and stirred into drinks.
We've been on the programme for 3 months and we are so pleased with the results so far - DS is much happier and easier to manage. We are still having some bad days, but they are nothing like as bad as they used to be. In fact they are a reminder of how far we've come. He is sleeping better, calmer, more obedient, has started singing and drawing, he's stopped hitting as much, has become more open to new things and is able to concentrate on things slightly better than before. His temper still flares up and he finds it very difficult to express himself when he's upset - he just sits down and cries... 
I think its def worth a visit and a weekend sounds like a good way to do it. There is a motor museum near by (good treat afterwards) and it's a nice area to visit.
I know what you mean about not wanting any more anger or stress in the house. It is a small daily effort and you have to keep it up. I asked Robin why it doesn't work for some people and he said you have to do it, day-in, day-out. It doesn't take long but at first it was a pain when everyone is tired or its late. We now see it as being like brushing our teeth - just part of our routine.