You would need to take a law degree for starters....budget at least 3-4 years for that.

If you have a law degree (it is a BA at Oxbridge but an LLB at new unis) then you need a one year Legal Practice Course. If you have a non law degree, you will need a one year Common Professional Examination, followed by the Legal Practice Course. Then you need to find a law firm prepared to take you on as a trainee solicitor (formerly known as an articled clerk); the training lasts two years and is not particularly well paid: I believe the Law Society recommends wages of ukp 14-15k in London (of course if you land a training contract with a city law firm in London, the salary will start at perhaps 25k or so - but these firms get 10-20 times more applications than they have training places). There is something called the "City LPC" which is supposedly geared towards the needs of the city law firms, I don't know much about it except that it has only been around for a very short time - a year or two I guess. My advice would be to not even think about it, unless you already have contacts with a law firm and a reasonable chance of getting a training contract somewhere - there is so much competition out there that you risk wasting years of your life otherwise.

To respond to the above; certainly trainee solicitors do not earn a great deal of money but the successful ones make a LOT of cash. In any event, a law degree and law school training is popular in the employment market Insurance, banking and finance for some: you do not have to use that training in a solicitors practice. Also a lot of companies have in-house solicitors.