The problem with CGT is it incentives the wrong behaviours. PAYE employees and small business owners have the same rules around how much you can contribute into a pension tax free per year.
Any tax breaks need to come via a separate mechanism and they should always be focused towards the very early stages of a new business (everyone has to start somewhere) and encouraging growth of SMEs by taking on employees who are subject to PAYE, not maintaining established "one man band" business, with the wife, cat and budgie listed as directors. As in reality they add no more value to the overall economy than a PAYE employee.
This would obviously need rules to prevent people exploiting the system by setting up multiple businesses or recycling businesses (disolving and then reopening under a new business name) to maintain the tax break.
From a UK point of view, its not a problem of people not setting up businesses, its our inability to grow and nurture SMEs to become large national and multinational companies and preventing them being swallowed up by other multinationals due to lack of investment.