The Further Maths Support (FMSP) produce resources for all A-level modules. One of these resources is sets of 10 multiple choice questions with written solutions for each topic. There are some sample resources on complex numbers provided free of charge on their website on the topics of:
Introduction to complex numbers
Equations and geometrical representations of complex numbers
Modulus and argument
The questions have been reproduced as .tns files for use on the Nspire handheld. Ideas for using these files, particularly using them in conjunction with Naviagtor are given in the teacher notes.