There is no difference between the single pilot IR held by a PPL or a CPL or an ATPL.
Yeah, yeah, yeah, I know. What I meant was that there are no standalone course materials or standalone courses for PPL people aspiring to have an IR. Instead, the only course materials and courses I could find was for people who want to end up with a CPL+IR or ATPL (which includes IR), so in those materials the IR specific stuff is integrated with the CPL stuff or ATPL stuff. In fact, when I enquired a year or so ago the exact advise I was given was to do either the ATPL or CPL+IR theory since the books were almost exactly the same as for a standalone IR and the costs would almost be the same too.
I cannot help but thinking that that's where the myth comes from that you need 707-type fuel planning knowledge to do the IR exam. Oh, and you'll be sharing the classroom with people for whom 707-type fuel planning will be an issue later in life, and as such, if it comes to that, they'll be freely discussing it during the IR portions of the course. While I probably will not be doing anything more complex than managing the fuel in a 172. (Which apparently is so complex it needs its own thread anyway.
)