Good for you The Window Girl. Good idea at the start is keep it as simple as you can and focus on doing a good job and getting as much custom as possible. So you'll be self-employed at least in the early days. Personally I wouldn't mess with being a Company especially at the start, I'd be self-employed and get on with cleaning the windows and pulling the cash in, anything else can come later if at all.
Not exactly in answer to your question but some tips I hope you'll find helpful. I have a window cleaner for my shop, an older man who does a good job and who also after doing that job hands me automatically an invoice/sales receipt - just a tear out from one of those self-copying books you can get at any office store and many Post Offices and corner shops. So he's got a copy and I've got a copy for my records to show why I paid out x in cash that day.
I asked him to do my windows after seeing him do a good job on other shop windows and popping in to ask the owners of those shops if he was reliable and if he gave you a proper receipt for work done. Answer yes to both so I approached him and asked him to take on my premises too. Point: it doesn't cost a lot to have some simple business cards or leaflets in your pocket which you can hand out to anyone who takes an interest and, if you happen to be cleaning windows for small businesses most will be happy to put your business card on their noticeboard or in the window. Some home owners will be willing to put a card in their window too - never miss a chance to advertise for free.
I also like my current window cleaner because he will clean once fortnight, or once a week or once a month or whatever you want. I go for the once a fortnight option which suits my business. It is built into the bargain that when he comes round you can ask for the insides of the windows to be done as well (or to be done next time). This flexibility was a big reason for me to ask him to start doing our windows.
