Law grads earn the highest amount, on average in the UK at £65k base salary + bonuses [average city bonus is £20k]. Software engineers earn around £30k salary + stock options [stock options useless in this climate, but in the late 90's made engineers millionaires, and it will happen again in the late naughties].
So, if Law is your passion then I think it is a wise choice to pursue that career, given the copmensation package.
Large Solicitor firms have graduate schemes, and the most well known one, I believe is at Clifford Chance, Canary Wharf.
They will give you £7k or so to go to Law School before joining the company. Applicants must be shit hot to get in - so good luck!