I would add that you should treat your £1000 turnover business like its £1,000,000 from day one, put your systems in place early on, order numbers for written purchase orders, sales order numbers for sales, order acknowledgements, expense claim forms and records, once you have staff even if its only one person, holiday forms, sickness records etc. Once you employ 20 people the systems will be there already, and the VAT, and NI will be easy because it will all be recorded, from day one. Your accountant will love you because he is used to getting a cardboard box once a year with everything in and will be able to spend his time reducing your tax bill rather than finding your petrol receipts.
God was I really that Anal