Having SEN &/or having a diagnosis doesn’t automatically result in an EHCP. If you think an EHCP is required, you should request an EHCNA. On their website, IPSEA (a charity) has a model letter you can use. You should take charge yourself rather than waiting for professionals to do it for you - they may never do it or it may be months/years down the line,
Without an EHCP, you will be limited to mainstream schools you would get a place at via the normal admissions arrangements. You would need to look at the schools’ oversubscription criteria and the data on the last place offered in recent years. You can state preferences (the number depends on where you live) but there may only be 1 realistic school. SEN isn’t taken into account in oversubscription criteria unless the school has an exceptional medical and social needs category. Where schools do have an exceptional medical and social needs category, it isn’t easy to be considered under it. The bar is fairly high. Most DC with SEN won’t qualify because all schools are expected to deal with most types of SEN. In the minority of cases where it does apply, you need professional evidence that only that school is suitable. It will need to say “In my opinion…” rather than “Mum says…”
The exception to the above re being limited to mainstream schools is if your LA has specialist early years assessment places for those who are going through or need to go through the EHCP process.
With an EHCP, admissions aren’t via the normal admissions process. You would be able to state your preferred school. This could be a mainstream school, including schools you wouldn’t normally be given a place at, e.g. if the school is oversubscribed and you live too far away. It could also be a special school. There are limited reasons the LA can refuse to name your preferred placement. However, that doesn’t stop LAs refusing and forcing parents to appeal.
@Cinnamoncupcake you need to request an EHCNA ASAP. The process takes 20 weeks if you don’t have to appeal, but many do have to appeal, some more than once. If you need to appeal, you need all the time you can get. You won’t have a finalised EHCP be the normal admissions deadline, therefore you must submit a normal application just in case because there is the chance you will not have an EHCP by next September.
If 1:1 is detailed, specified and quantified in F, it must be provided and can be enforced. Focus on that rather than funding. If your preferred placement is a SS and the LA doesn’t name that, you can appeal.