I went ltd and VAt reg from day one, first year T/O was £40K.
I have to do the following.
1. Set up Ltd company with companies house, bit of a faff but straight forward. About £40
2. Annual return to companies house for any changes to company set up (£13)
3. Annual accounts (short form, ) - takes me 4 hours on a Sunday , these go to HMRC and Companies House, all online
4. VAT every quarter, takes me 1 hour.
5. Monthly PAYE return to HMRC, takes 15 minutes
6. Annual PAYE return, takes 5 minutes
Thats it, you are required to keep decent records and yes i have folders and folders of paper but i would have kept these records anyway even if sole trader.
So it costs me £13/year plus 11 hours work a year.
Its not for everyone but i prefer to do it myself, at the end of the day, if your accountant gets it wrong, its your bag to sort out and if HMRC come calling, its you they come to and you will have to pay your accountant to handle it. My business is very simple, no fixed assets, no clever stuff, just invoices to clients, invoices from suppliers, PAYE and expenses...