Account set up and Horizon+ activation

So I have 2 problems which may be connected, my son got a Meta Quest 3 512Gb for Christmas, i was trying to set up the account for him so used his screen name, this was before I realised that the account i was setting up was for me as he is 12, that means I now have his gamer tag, is there a way to transfer this across to him as it is only him using the VR? Secondly when purchasing the VR it stated there was a 6 month free subscription to Horizon+ i cant find a code for this anywhere or a route to claim this offer, we are in the UK and it was bought from Argos, any ideas

Any help resolving these 2 issues would be much appreciated

And a 3rd question, is there actually a support team for meta or is it only through these forums i can get help?