You don’t need to pay for someone to explain the EHCP process. Have a look at IPSEA and SOSSEN’s websites and read the SENCOP.
If you don’t have to appeal, other than a few limited exceptions, if the LA is going to issue an EHCP, they have 20 weeks from the EHCNA request to finalise the EHCP.
If the LA is going to issue an EHCP, when they send you the draft, you will be able to state your preferred placement. Unless the school is wholly independent, there are limited reasons the LA can refuse to name your preferred school. Wholly independent schools have slightly different rules.
You can start investigating schools now. However, if you are looking at special/specialist schools, many wouldn’t speak to you at this point. Although that doesn’t stop you asking around locally, reading policies, looking if the schools have any public events (e.g. Christmas Fair).
Personally, I wouldn’t use an education consultant for advice about schools. Particularly at this stage when you haven’t requested an EHCNA and haven’t had assessments to inform the provision required to meet needs. I would save your money in case you need to appeal and fund independent assessments.
Be careful with SENDIASS. Some are good but too many repeat the LA’s unlawful policies.