I've worked a number of software roles (around 10 in the last 15 years) in the UK. Only been asked to sign away my working time directive once, and that was for an American owned company. I declined to do so, and still got the role.

When I worked in the UK (3 jobs over eight years) I was never asked to do that; the closest was that I was ask to sign as to whether the 48h/week limit would apply week-by-week, or averaged out over 17 weeks (as per the regulations).