You must submit your school preference form by the deadline, but there's no benefit or drawback with doing it early, so you don't need to rush. As someone said, in some LA areas you can log in again and amend your preferences as many times as you like before the deadline, but our LA recently stopped allowing this, so you will need to check.
OFSTED reports are useful, but are not the be-all and end-all. You say you're new to the area - is there anyone you know that has a child in the school currently? If not, can you ask at any local groups you might be involved in, or nursery, the local library, corner shop etc? Avoid old feedback - it is really only relevant to hear from people with current knowledge of the school.
I would definitely follow up with the school to see if they can arrange a visit. I think you might have left it a bit late as they tend to do them in October, but hopefully someone could at least chat to you. Do you have any particular questions pertaining to your child's needs/interests?
Although this is your local school and, all being well, will be a school you're happy to send your child to, it is also a good idea to check out the next closest schools, as it's better to have more than one option. Obviously, depending on whether catchment areas apply or the distance criteria for the local schools, you may not have many options, but it's worth checking.