Wandering try using the HMRC Employment Status Indicator to determine whether or not you should be an employee or whether, for tax purposes, you can be deemed a freelancer. Read the blurb on that page first, then click the link at the bottom to go to the ESI.
If you carry all the risk and provide all of the equipment required to provide the services you provide for this company - e.g. you have your own IT equipment, phone, no company email address etc - and you can carry out the work in your own time with minimal direction, then it is possible you can be deemed self-employed.
If, however, they are simply paying you a freelance fee but you are to all intents and purposes carrying out your work tasks in the same way and under the same conditions as all actual employees, then you would probably be deemed an employee and can claim against the company for backdated pension, statutory holiday pay etc and the company could be fined for not paying Employer's NI.
There are a number of factors that need to be taken into account when determining a person's status but job title is rarely one of them. Freelance/ self-employed/ consultant etc often mean the same thing - that the person is not thought to be an employee. Companies frequently get this wrong though. There are a lot of maybes/ probablys in my post because it is not a clear cut issue.
As for the shouting thing, unless it's a really small company you should ask the HR department about the company's dignity at work or bullying/ harassment policy. Regardless of whether you are an employee or a contractor/ freelancer you have the right to be treated with dignity at work. I have never shouted at anyone at work (even if I felt like doing so), regardless of their status, and would expect to be disciplined if I did.