@KisstheTeapot14 Great questions!
With regards to qualifications - In my opinion you need some. It is one thing to have a degree in a subject, it is entirely another to have studied how to teach that subject to someone else.
If you are in a position where you could study a PGCE, go for it, you will without a doubt learn a lot and it is a well-known qualification. But it's a very full-on course that takes at least 1 year.
But there are other, shorter routes that I think are also very valid. I hold two PGCEs (from England and South Africa) and I also hold a CertTESOL and Certified Tutor Status so this comes from personal experience.
TEFL/TESOL courses are very much worth it, if they include a practical component. Don't be fooled by any of those "online only" "get it done in a weekend" nonsense courses. Employers see right through them and it's very much like doing a weekend first aid course, it's an introduction, it's certainly not enough to make you into a paramedic ;)
Given your personal experience with SEN, I would encourage you to specialise in that - you will have more credibility as you have worked long-term with these challenges and you will have the dual insight of being a parent and an educator.
There are lots of short courses run by organisations such as the Autism Education Trust. If you currently work in a school, you may be able to access these for free/reduced rates as part of your CPD. In my experience these courses give a lot more insight into specific needs (e.g. dyslexia, autism etc) whereas the broader courses like a PGCE or a CertTESOL don't have the time in the curriculum to explore each SEN in such detail.
Volunteering - excellent idea.
You have years of experience with your own son and this is a huge advantage. If I were you I would definitely emphasise that on your CV or when advertising yourself.
But now you should focus on small group tutoring, as that presents its own challenges.
There are lots of Access courses that you could pursue part-time while volunteering too, e.g. Level 2 quals in Teaching Assistant, or Supporting Teaching and Learning. Check out the NCFE CACHE website. I have taught a Level 1 CACHE course and several of my students went on to do Level 2 courses while also volunteering at their children's schools.
I would also insist on Safeguarding training (though again, if you already work in a school you should be getting that annually) and an Enhanced DBS check. Safeguarding training can be done online, there are a myriad companies that offer it. Getting an Enhanced DBS check is easy if you work in a school, if not, your volunteering placement can help you get it.
What I wish I had known before I started tutoring - Well, at heart I am a teacher, not a business woman, and it has taken me a while to learn business skills such as having a cancellations policy, managing payments and invoices and that whole side of things! As teachers we just want to help, help, help BUT if this is going to be a source of income for you and your family, you need to set boundaries in place and run it like a proper business.
I use Tutorbird to manage all my client details, invoices, calendar and so on. They have an amazing customer service team who can always help.
I have also been doing some business courses to help develop my marketing and finance skills. Registering as a sole trader in the UK is very straight forward. But then there's a lot to consider, like will you offer a free trial lesson? Will you charge in advance? Will you advertise online/offline? Will you work on Bank Holidays and during half-terms? But all these questions eventually do find answers and to me it has been a really rewarding journey :)
Although if I am ever able to hire an accountant to do all the boring admin bits for me, that will be the dream!