You can file online (see https://ewf.companieshouse.gov.uk/help/en/stdwf/doclist06.ht... ). Bear in mind that signing up for webfiling can take a long time. Don't leave it to the last minute.

Life is much simpler as a sole trader though. As far as I can see the main reason to form a ltd company is if you want to employ people. I started a company because its the most tax-efficient way for me to invest consulting money into a future business.