I am currently doing my level 2 and will start my level 3 in Sept.
I go to college one evening for 3 hours and do 2 days in school. I had to find my placement before starting the course and currently it is on a voluntary basis, but I am hoping once I qualify, I will be employed, if not by this school, another one and start getting paid!
Assessment is done by your coursework, it is split into units and you have to do produce various pieces of work for each one, which your tutor will grade. If something is missing, or it isn't enough info to demonstrate your knowledge, when you hand it in to be marked, you get a chance to do it again. At the end of the course, an outside assessor may look at it too.
At school, you may have evidence sheets for you mentor/ class teacher to fill in and an assessor will also come in and watch you in the classroom and try and look for as many relevant things for evidence of your understanding and doing the role that they can - things like ' communicating and interacting with Children' and other things that are listed. It could take two or three visits, depending on what you may be doing on the day they come in. Sometimes the assessor will get a huge amount in one visit for a couple of hours.
You can find the units and details of hours that you will need to have as evidence if you do a search on the Internet.