I was writing this off-line and
@Clivethedrive beat me to it ! Thought I might as well post it anyway.
Well, I don't know what you've been told and maybe it's good information. But most of us feel that the NHS is a little
behind the curve when it comes to dietary advice.
One poor chap recently reported being told to increase his carb intake when most diabetics would advocate reducing carbs. The adult reference intake of carbs is 260g per day and most of us are down at around 150g with quite a few below 50g. I cannot tell you how this scales down for a child though, you'd need to check this.
Things like pasta, rice, potato, cereals, and bread are all in the carbohydrate food group and the body turns them all into glucose. As you've already discovered, most fruit isn't great for diabetics either. Great isn't it. Your son can still eat this stuff but you need to be aware of what it will do to his BG levels if he has big portions. Again, this is where the blood testing comes in.
If he likes a chocolate treat, then many chocolates with a cocoa content of 70% or higher have less carb content than the special diabetic chocolates available from Boots, (something else designed to trip you up). We recently discussed chocs' in one of the threads and you can get inexpensive high cocoa chocs at places like Aldi and Lidl if you have one near by.
People on ultra low carb intake compensate with increased protein (meat, nuts, fish), fatty foods (dairy) and vegetables to stop hunger pangs. Of course, reducing carbs to this level and increasing fatty foods would never be advocated by the NHS and may not be appropriate for your son. You must decide whether or not to go down this route for yourself.
Knowing what to feed a diabetic child must be a nightmare but i'm sure you'll get on top of it. I'd just like to suggest that you proceed with caution and ask questions about specific things if you need help. Good luck.
