Many thanks both of you for your advice.
Any ideas on how it is likely to affect job prospects?
I have seen airlines stipulate that the CPL and IR are to be completed at the same FTO, but nothing about whether it needs to be done in one go or not.
I am not overly concerned about the difficulty of either of them on a personal level, as I will be able to take time off to do them both full time. It's just that there will be quite a significant gap between them.