I've just completed my CPL/IR and I wouldn't have wanted to take 3 weeks out of the training to attend a brush up and the exams. I think that continuity of flying is important and if you have a big gap in your training you will probably end up taking more hours to pass your test. More hours not only equals more money but some airlines do look at how many hours it took you to pass your tests.
I studied at BGS and between Mod 1 and Mod 2 I gained my MEP rating. This helped me feel like I was getting somewhere and also meant that when I did my IR I was already familiar with the Duchess rather than going in cold. I also kept flying the PA28's every few weeks to take friends up.
Ikea I would say get your exams out of the way and then put all of your effort into the flying.