I think you definitely made the right decision - making your choice from your own family's best interests and NOT what his friends are doing.
I went up to Ribston with 2 other girls from my school - one was my BEST friend (!) and the other was in my friendship group. They split us up into 3 different tutor groups, and I didn't speak to them again after the first couple of weeks, until after I left at 6th form! My 'best friend' made a new friend in her class that didn't like me and she told her not to be friends with me anymore, so thats exactly what happened! It wasn't until I had my first child that we got back in touch and are now very close friends again! So I wouldn't worry about that in the slightest, he can still keep in touch I'm sure if he feels like he wants to, but I guarantee he will make new friends instantly and not be concerned with keeping in touch, at least not in the early days.
It must feel very frustrating to have been given such dud information, but as no-one really knows where they are going until March its difficult to use that info anyway - for example, unless all 4 of them were within PAN its possible that they might not even GET Tommies anyway.
On another, slightly selfish, plus - I put Pates as 1st choice for my DD so I'm glad to 'meet' someone else who my DD and I might come across over the next year or so

Fingers crossed we get what we want!!!
PS regards the whole 'friends from Ciren and Swindon rather than just round the corner' - I have the same reservations and part of me wondered if I should push her for HSFG for that very reason but we looked at all pros and cons and in the end, she was adamant that she wanted Pates and she fully understood the implications re friendships and actually she's really looking forward to a fresh start, and not knowing anyone etc. She's looking forward to using the school bus as a social jolly as she know she probably won't spend much time with friends outside of school, but she doesn't do that at the moment anyway so she's doesn't know what she would be missing out on. I've suggested to her in the future perhaps she could pop to Chelt town with her friends (providing they don't need to catch a school bus) after school every now and then and I can go pick her up later on or she can get the 94 back to Glos.
Hope you feel better about it - we do put so much pressure on ourselves don't we?