At last someone putting a bit of thought into things! Retiring at 40 -did you make WO1? You mentioned a class 2 medical. Get a class 1 done asap (i think there might be more tests after 40) I'm sure it won't be a problem but it's better to be on the safe side.
As for the route to ATPL, I think convoluted can be better, as it sets you apart from the integrated boys who have nothing to talk about in interviews!
The order of things is personal preference, CPL has the biggest hour limit so it makes sense to do it last IMHO. I think the CBIR is a brilliant thing - 55 hours for an IR is too long anyway. Doing an IRR then 15 hours of 'Actual' and finishing up with 10 hours at an ATO is more beneficial because you can count it all to TT, and 15 hours to PIC. As for the multi, once you've got the IR cracked, you're just adding an engine failure into the mix which is shutdown and securing drills on the go around then finish the test SE. Two IR tests, but cheaper overall.