Would really love your opinion on this please. My head is swimming!
We are relocating from Buckinghamshire to the New Forest in the next few months, probably Brockenhurst. We will be moving into rented accommodation to get to know the area better before buying.
Depending on the timing, we will be looking at either an in-year Year 2 place or a Year 3 place for Sept. I have contacted a number of schools in the area and they all say they are full. Some already have waiting lists with siblings on, and so they would get priority. Brockenhurst Primary seems to have a class size of 34 for my son's year! 
DS has sensory processing/integration issues. Some of them aren't relevant at school per se but he is sensitive to noise and can be easily distracted. I don't feel therefore that an overly large class will be right for him. What is your view? However, as we will be moving to a new area, would the benefits of going to a local school and therefore making friends more quickly outweigh this?
Where we move to is flexible, as we only have to balance DP's commute up the M3 and DS's school. However we need to rent somewhere in the area before we can apply and then this will restrict us to that school catchment! As we're moving to a new area, we'd like DS to go to the school closest to where we live, so that he socialises better and settles in quickly.
As Brockenhurst is in catchment for two secondary schools, we're thinking this would be a good place to settle. If DS has to go on the waiting list for Brockenhurst primary, the only choices available to us are either home schooling or the private New Forest Small School, which has much smaller classes (we'd struggle to pay private fees, tbh, but would do so at a push). All the other primaries are full, and we wouldn't be in catchment for them anyway!
Any advice on the Hampshire admissions procedure, or relocating to a new school catchment area? This is really doing my head in! 