Forget about legal and accounting implications for a second and look at the tax implications.
Any profits you make from trading/investing through a company will effectively be taxed twice in most situations that I am aware of-they will be taxed as profits in the company and then you will be taxed on receipt of dividends or salary when you extract money from the company. There are also close company provisions specifically applicable to investment companies that may also be relevant.
But if you are considering investing as a full time occupation, the 'sole trader v. limited company' issue may be worth teasing out in more detail. I strongly suggest that you contact a tax professional to discuss this in more detail if you are serious about persuing this as a full-time venture.
FWIW, the setting up a company to invest in property is a Key Post in the Property Investment forum.