You need to enable the pixel aspect ratio toggle for your comp window.
Your standard Pal comp (4:3) is rectangular pixels.
It looks like they want a standard PAL Widescreen product, which is also rectangular pixels. Working inside AE in Rectangular pixels is not usually a good idea if you ever think you will need to show the product on the web or a mobile device. That's why your comp looks strange. There is a pixel aspect ration correction button that will fix the display problem, but I have a better idea.
I would choose the Pal Widescreen Square Pixel composition for my project.
Then render a digital intermediate and then use the Adobe Media Encoder to render your final output using the Mpeg and then use the PAL Widescreen preset and set up your encoder something like this. Make sure that you use Two Pass encoding for maximum quality. You should be able to find all the settings you need. Don't forget to check the audio section. (and don't forget to check your audio in Audition before you render your DI also. You can't really see if your audio meets the levels spec in AE very well.
thank you mate, that sorted it out!
Thank you for your in-depth answer, Rick - and sorry for not accepting your answer as correct: Szalam's answer answered the question, however your analysis proved to be very helpful while rendering the comp. In fact, your insisght is spot on: I used to make these comps in Flash because they were meant to be used for purpose-built Flash/swf-playing equipment. The simplicity of the previous tasks got me spoilt, I got a bit slack on reading up I guess...
Thank you again!