Z4 door/bowden cable issue

[parabolica]

Found out today my driver's door doesn't like to open from the outside when it's warm/in direct sunlight; the handle is fine but it's like the cable has snapped and won't open the door. However it does open if you press your knee against the door and apply some pressure and it opens fine from the inside. Just been back out and in the cooler temp, the door is happy to open again however it is evident the mechanism has deteriorated as the latch only just uncouples with the handle pulled fully up.

Reading up on it, it looks like the bowden cable might have stretched; replacement cable is only £10 but there are varying experiences online about people changing this out; some saying it was easy enough to do, some saying it was a PITA. Has anyone here done it (or similar; I believe BMW's door mechanisms are the same across the entire range) and if so was it easy enough to do? I think the main PITA bit is about getting to the actual door handle from inside the door.