I freelance and just use my own name. I thought about setting up a limited company but not worth it for my earnings.
However I freelance for several companies, sometimes up to 5 in one week. If you are only working for one plAce and doing hours dictated by them then you are an employee and they are probably offering freelance as a way of avoiding paying employers NI and you will have no employment rights.
How are they going to pay you? If you are invoicing them then check how long they will take to pay and tell them what your payment terms are. Ie if they take 30 days then invoice at the end of each week, don't wait to the end of a month.
Also check whether you are covered by their insurance, you might not be. I have indemnity insurance which costs me about £250 a year. Are they expecting you to use your car for business purposes, in which case you will need a more expensive insurance policy to cover business use.
If you use your own name the you are ok to pay the wages into your normal current account as its your wages. If your set up a limited company then you will need to open a business bank account in the company name and business accounts can incur high charges.
You will have no employment rights, not even covered by the agency workers regulations, so they can finish you at any time, and if they finish you and theres money outstanding it can be difficult to get paid.
Once you have registered with hmrc as self employed I think you can be entitled to statutory sick pay, but no dole if you are out of work, (check those ladt two out, ive been self employed 6 years and never needed to claim). So if you hav eto ring in sick you will get no money at all for a few spdays till ssp kicks in. however you can claim tax credits.
Tax return for straightforward self employed is nothing to worry about, keep a record of all money in and any expenses.
Don't mean to be completely negative, just trying to let you know what to look out for!