Take a look at the Cambridge ESL CELTA website:
Cambridge ESOL: Certificate in English Language Teaching to Adults (CELTA)
At the bottom of the page is a pdf of the course syllabus.
Every day, you'll have seminars in the morning. Over the course, you'll cover all the areas on the syllabus in your seminars.
I had 9 teaching practices, each 40 minutes long. Each of us had a TP every other day: in groups of six, three taught on one day, and three the other day. We watched and evaluated each other. (After each TP, you write up your feedback on your teaching then bring it in to discuss in a group the next morning.)
On days when you're not teaching, you're planning lessons. There were 11 people on my CELTA course. Almost every one of us needed a whole evening - and a bit more then next morning - to prepare a single lesson. (Planning gets a lot faster once you're teaching 25 lessons a week in a language school, thankfully!)
On my course, we were given a textbook and told which chapter the group would use. Then, as a group, we had to decide who would teach which material, making sure each of us taught at least one lesson for each of the four skills, plus vocab, grammar, and possibly collocations lessons.
You also observe more experienced teachers several times during the course. There's a task for each observation.
There are four assignments, which will keep you busy during the evenings and weekends that you're not planning lessons or writing feedback. Some of the other CELTA trainees in my group failed an assignment. If I remember rightly, they had one day to bring it up to pass standard (and couldn't get a better mark than a pass on that piece).
Be prepared to drop everything in your life except eating and sleeping a little over the four weeks of the course. I was getting up at 6am and arriving at the school early to do some work before the teaching started - and studying at break and lunch times - and going straight home at the end of each day to work until going to bed at about 1am.
Two guys on the course didn't work that hard, but the other nine did. Of those two, one only avoided failing by doing an extra teaching practice on the last afternoon; and the other had been teaching for four-and-a-half years before doing his CELTA.
As I said, you evaluate yourself, and the other students evaluate you too - but the judgments that go towards your grade come from your CELTA trainers. Basically, they have a big list of competencies they're looking for you to demonstrate, and they tick them off as you go through the course. You have to pass every criterion.