Thanks Triplets. 
He wants to be a gunner in one of the Reconnaissance regiments. He wanted to Infantry for a long time, got fit for it, then changed his mind three days before his interview!
We wouldn't let him join at 16 because we wanted him to do A levels, which he did, so he can still go for his commission. He has wanted this since he was at primary school.
He went for selection in April and was in training by July. He said it is like being in a hamsters wheel, it is continual and long days. He has to get up at 5:30 and in bed at 11:00. (They are checked they are in bed and lights out 
). He has had a bad day where he wanted to come home, but only once, but he is happy and enthusiastic. He got his first months pay on Thursday, he said he has never seen so much money in his bank account!
We had to drop him off on the day, DH and DS2 had a camp tour I didn't go because I am disabled and couldn't keep up so I had a chat with the Major. When we left I cried like a baby, as did most of the mums. They have their phones and we ring or text most nights. I give him little pep talks. He can come home for the first time in 2 weeks!
They like to see that they are receiving parcels, so we and PILs send things like cereal bars, toiletries, Jelly Babies, cards and letters on a regular basis.
It is really odd not having him at home. But every time I talk to him he has something new to tell me and has achieved something else. I'm really proud of him, I do have little cries every now and again, because I miss him but I am so glad he has done what he set out to do.