Teacher

Qualifications needed:
If you wanted to become a lecturer fifty years ago, a post graduate qualification was not necessary, but the career has become so professionalized over the past few decades that now it is nearly impossible to get a permanent lectureship without having completed a Ph.D. The qualifications that you will need are a good Bachelor's degree (2.1 or above), possibly a Masters, and for almost all disciplines a Ph.D. in the relevant field. You do not need a separate teaching qualification, although you may be offered the chance to do one while studying for your Ph.D. Alternatively this may be required during your first year in the lectureship job.
Teaching Experience needed:
I hope that while doing your Ph.D. you have been planning your future career and working out ways to maximise your chances of getting a job. There are two main aspects to being a lecturer: lecturing (I. e. teaching) and research (with administration running a close, often undesirable, third). Different institutions prioritise research and teaching slightly differently and you need to find out which aspect is most important for the particular job you are interested in. As a general rule for the UK, Russell Group universities prioritise research whereas post-1992 institutions place more emphasis on teaching, but this is only a generalisation. Let us take the question of teaching first. While doing your Ph.D. you may have been offered the chance to do some teaching in your department on an hourly rate. A few universities discourage this, but most have realised that gaining teaching experience is important for future academics.
This is usually in the form of seminars or tutorials, but occasionally you will get the chance to contribute towards labs and lectures as well. You may be asked to mark essays and even help mark exam scripts too. This is where you will gain the experience needed to get a permanent lectureship after your Ph.D. Make sure you do as much as possible to build up your skills portfolio and expand your teaching experience. Without this experience you will find it pretty difficult to secure a teaching job later on. It is wise to take any teaching work if it is offered, even if it seems to be a distraction from the main aims of your Ph.D. One aspect that many Ph.D. students do not get involved in is curriculum design. Rather, they have to teach courses designed by others and do not have a say in how and what they teach.