Drop me a message when you’re seriously wanting to start up and I’ll give you some more focused advice.
But it’s always better to start super niche and then work your way outwards.
Grab a copy of this – https://www.amazon.co.uk/22-Immutable-Laws-Marketing/dp/1861976100/ref=sr_1_1?dchild=1&keywords=laws+of+marketing&qid=1622802170&sr=8-1
Make note of how it talks about creating niche markets rather than trying to break into established ones.
Medical sales training is a strong niche as you can’t automate sellers being hands on in the clinical environment with a “4-part video guide”.
I’d see if you can start sales training internally in your own organization.
Being able to say “I was the head sales trainer at XYZ” and prospecting their competitors is a good starting point to make the leap into sole trader.