The optimum salary for most small businesses is often to keep the salary below the level at which national insurance becomes payable.
E.g. fuel, telephone - expenses that are not tax deductible for a sole trader or partnership but are for a company.
Benefits that may arise from having a company (e.g. car and fuel benefit)
Companies under your control including this one
Extra savings possible by not extracting dividends that put your income above the basic rate tax band.