Self employment on tier 4

[stephalphs]

Can someone please advise me accordingly.
I was on PSW and was working for my company on self employed basis.
Now I will be receiving my BRP soon on tier4, and I know I cannot continue to work as self employed.
My plan A is to register with an umbrella company to get my wages paid.
However, I would like to clarify something. Tier4 said I cannot be self employed, but it says nothing about the percentage of shares I can hold in the company I work for. I remember for tier 2, I think they cannot own more than 10% shares. Does that mean I can own even 100% shares of the company I work for on tier4? So can i effectively set up a company, and then work for that company?
I would like to avoid the umbrella company because of the fees and cuts involved.
All input will be much appreciated