Could anyone advise re modules 4, 5 and 6 of A2 please

Not done it before and moving back to Nuffield  with new year 12

Is it possible to enter for 4 and 5 in Jan and leave only 6 for June??  Does it work?  I am tempted as it will give two goes at 5 if required?

The old rule re so many percent at end has gone hasn't it??

Claire Emery