After 25 years in the NHS, I went self-employed just about two years ago. There is a lot more freedom, but there is also a lot of uncertainty; the work tends to be "feast or famine" and you daren't turn anything down in case you have a shit couple of months where there isn't much going on. I've sort of got used to it but there are a lot of things I miss about the NHS (including what I've lost out on in pension).