Theres one problem
The one problem with doing the ME IR first is when you return to the CPL you find your head is always in the cockpit. Plus you might do the CPL in a single which is depressing after being in the twin, be realistic your CPL will probably take you 20hrs if your not held up by weather. Then who knows! The students who have the CPL and come here are by far better pilots on arrival as they have the basics on Instruments. My advice get the CPL done while the weathers good in the U.K