The are lots of good school close to the centre. The first thing you should do is phone them direct and ask about availability in the ds's year group.
Try HTPD, Sandfield, St Nic's, Onslow Infants, Boxgrove and St Thomas' depending on where she plans to live. Personally, I would aim for an all through first off as an infants only will have some uncertaintly about which juniors next and he's already interrupting friendship groups once.
HTPD should offer really good pastoral care for him and I think St Thomas' would too although it's less central. He might get special consideration if there is some SS involvement due to the father etc. It's worth asking.