Teenage boys are programmed to be repelled by their parents, no matter how close they are to them, and living with them can be extremely quite bumpy at times.
Your son may be adorable now parsley but he is going to change soooo much over the next two years you just won't believe it (he will still be smashing, of course) and he will begin moving away from you at this age anyway, and is going to want to spend much more time with his friends than with you.
Boarding school can deal with this stage admirably. He is surrounded by friends, he has caring and sensible adults to talk to about stuff but who won't say stupid things, and won't 'keep going on at him' and who won't incinerate him with embarrassment by trying to be friendly with his friends, he will have any number of cool role models in the older boys - whether they are first team rugby players, comic actors or super geeks. As for GCSE time, it just worked brilliantly.
You will miss him like mad, (although you are used to him boarding anyway) but when he comes back the first thing he will say is 'It's just so great to be back home' and will be happy to revert back to snuggling up with you to watch DVDs and catch up on the gossip.
Ignore kitkats comments, she obviously has no direct knowledge and is just one of the anti-boarding sharks who like to come on and bite chunks out of nervous parents whenever they sniff a wibble or a waver. Real closeness has nothing to do with physical proximity.