yellow certificate requirements, application, and general help needed for a Croatian national

[lukaslocro]

Hi everyone, I'm Luka
I brought my roommate from Croatia, she is 25 years old and wants to work as a community carer on a self employed basis.
The problem that appears now is the following. Job centre says she needs a yellow certificate to get the National insurance number and on the yellow certificate it says you need to submit the details of your own company.
So the question is as follows,
if we fill out an application for a yellow certificate, is there any option to state that she wouldn't open her own company at the start, but would do so once she gets her cash flow and if you know where we could get help for filling out the application.
I want to get as much as possible done here now, so all is ready when she comes back. There is no reason for her to stay here, if she can't work here yet.
I've seen the reply from the home office can take a long time and some say it can be done within a week.
Just to state, that I didn't bring her here on my whim, I asked a recruiter, who recruits internationally, he said all is fine and all has been sorted with the company and the company doesn't know any better as well and it appears, neither does he, since he didn't call back.
I am sick and tired of people stating something is handled and then I get her here and it will be one month and still she can't work. Frustrating. I have to pay a months rent solo and it's not cheap.
If anyone can help, I'd appreciate it. I thank you for your help in advance.