Motocross Fields For Sale What Bike To Buy For A Fist Motocross/fun Bike For My 11 Year Old Son With No Riding Experience?

What bike to buy for a fist motocross/fun bike for my 11 year old son with no riding experience? - motocross fields for sale

I want my son to buy dirt bike for fun, especially in our country (around the local tracks are normal in France) but I'm a Road Runner and had no idea bikes.He off road use and has no experience ride my bike to 11 years and is about 1.5metres tall, weighing 40 kilos, and I want to buy a bike for sale in the United Kingdom, any help would be very useful.