HWD. You know where you can come to in surrey to be tought!
As for the cessna slip with full flap:-
1 )Think about the relative airflow in that condition
2) Think about what will happen to the airflow that passes over (and under) the wing (Into the slip)
3) Think about which control surfaces will be masked by aforementioned wing & flap
4) You have your answer!
Send Clowns. The ASI may Under or Over read depending on the direction of slip (Assuming only one static vent).
As mentioned by a pevious poster. The sideslip is part of the JAA syllabus (as it always was with the CAA syllabus).