Hi Dean,
As Fly Stimulator says you can obtain Night Qualification at the same time as your JAA PPL so yes you can obtain it before your IMC Rating.
Incidentially we're lucky we've got the option to do the Night Qualification at the same time as the JAA PPL or not. The Americans, unless they live in Alaska (FAR 61.110), have to do the night flight training before they can even take their PPL Checkride.
Anyway we're talking about the JAA system here.
As for the 70 Hours PIC before the IMC, that isn't the case. You require 10 Hours PIC which has been gained since the date of application for your PPL. However this 10 Hour PIC can be gained before, after or during IMC training. You will not however be able to have the IMC Rating issued by the CAA until you have the 10 Hours PIC.
The 70 Hours PIC requirement is for the Multi Engine Rating. If you were to go for a Multi Engine Rating, it maybe a good idea to do some flying in a complex single during those 70 Hours PIC. It'll make life a little easier when it comes to the Multi Engine flight training course.
Best wishes,
Charlie Zulu.