big.al,
This thread includes quite a lot of comments from several of us who were doing IMCs at the time. It should give you an idea of the level of difficulty in relation to the PPL, and how it feels to do the course.
In a nutshell, as with learning anything new, it seems quite challenging at the start but begins to fall into place as you practice.
I don't think any competent PPL-holder would be unable to achieve the IMC.