Hi,
I think this depends to some extent on the college or company. As an example, at the college I used to work for the 1st year students produced 10 'boards' throughout the year that each exhibited a different kind of wiring arrangement (ring, radial, 2-way lighting, etc). The final board was a complete installation and had a distribution board, lighting circuit, cooker circuit and ring final circuit and for their practical assessment the students had to test the board, record the findings and then carry out a fault-find. The students also had to complete a portfolio of work by answering questions about some of the boards, drawing circuit/wiring diagrams and obtaining technical documentation about the equipment they were working with.
For the second year, the students had a timed assessment working in the bays to complete a new installation. Prior to this they also had to complete a risk assessment questionnaire and a material requistions form as well as answer a series of questions relating to the regs and health and safety. For the installation, students also had to decide whether they were using plastic or metal conduit and prepare the material in the correct way. The students were also expected to carry out safe isolation before they begun the work, and also demonstrate their ability to make the working area safe.
For the third year, this was pretty similar to the second year but included fault-finding on a test rig.
I'm not sure how much guidance City and Guilds gives as to the content of the assessments so it's possible that different colleges and trainers do things in different ways. Most obviously, some of the colleges and companies run the course over 2 years instead of 3, or even run intensive courses of several weeks, so it's hard to know what you might be getting. That said, if you make a point of going to the City and Guilds web site and downloading the level 2 syllabus, you'll find out exactly what you'll be expected to know/demonstrate. This is a pretty long document (about 100 pages from memory) but it's an excellent way to check your progress by ticking off each of the tasks or categories as you go along.
Helpfully, the City and Guilds web site doesn't seem to be working properly at this precise moment
so when they feel like switching everything back on again, go to
http://www.cityandguilds.com/
put "2330" in the search box in the top right-hand corner, click on the link to the course overview that should come up in the search results then the course syllabus should be available for download on the left-hand side of the page.
Hope that helps,
Neil