upto you at the end of the day but i recon its worth getting it aligned first to see

a) how far its out now (camber and toe) and
b) how far its out after realignment.

you may be suprised. the toe may be way off and causing half the problem. you'll also know then whether you need to spend £150 on the arms.

oh and if removing bolts be aware that as ford didnt grease them they very easily sieze into the bushes which means cutting them out