My suggestion from my experience having been a sole trader for 3 years is
1) Sort out your public liability insurance, which will ask turnover type of business ect
2) Draft you business terms and conditions, most companies look favourably on small one man business, so you are likely to be paid 30 days end of the month.
3) whether you need an account is based on your diligence with your records and your understanding of business metrics balance sheet p&l etc. I went to a new business start up workshop spread over 2 days FOC. They gave you p&l and balance sheet templates which I used for three years.
4) Get receipts for everything
5) Decide how you will fund your vehicle travelling.
6) As a consultant I had limited purchases eg you dont buy wood or nails, but I had lots of incidental expenditure, internet/equipment/ ppe.
Lastly I ran a business bank account as it keeps personal and business separate, usually they offer 18 months free so shoul easily cover your original expectations
Im sure there will be more experienced folk who will chip in or correct me