I might be able to help a bit, I was freelance for 10 years as a self employed book keeper, and just become limited last September. So as self employed I would pay 20% tax on my profits, after the individual tax free allowance (10k for14/15), and perhaps in your case a slight bit of 40% tax too?
Whereas now I am limited, I take a salary of £10k via the business, tax free, I can legitimately claim for business mileage, business use of mobile, as well as the usual overheads I have etc...., plus I can take dividends taxed at 10% as long as I am a 20% tax payer, and then I received a 10% tax credit towards my dividend payments, so in short, no tax is due on the dividends. You must be a shareholder to take dividends, and you would be the director too of the limited business. You then pay 20% of the limited business profits.
Obviously being self employed you have one return to do per year to HMRC, whereas with a limited company, there is the Annual Return to companies house, plus the annual filing of the limited companies house, plus a self assessment for you to declare your dividends etc. So much more paperwork, hence, higher accountancy fees.
Also going forward, the money in the business , is the business's and not yours whereas freelance, its nice to have freedom to your hard earned cash! For me being limited is perfect as it controls what I take and spend, but then if I have to update computors etc, software, its nice that its coming from the business and not my own pot...
Good luck whichever way your choose x