The quick answer is that I think it will all look great - particularly in a pepper white/black car. That said...So now decided to go with normal headlining also getting Mini Yours Carbon Black Leather interior and Mini Yours Steering Wheel...Being pulled more and more to Mini Your Carbon Leather with off white interior and grey headlining. Would love to see any actual photos of the off white interior trim.
I LOVE my leather lounge seat (albeit in grey). They are very comfortable yet supportive. I also really like my MINI yours steering wheel - it's very grippy and looks good. And the 3rd gen normal headliner is more grey and less tan than shown in the configurator - I think it will accent the off-white nicely.
I read someone's post (sorry I don't remember which thread) who got the MINI yours off-white and LOVED the dash pieces - they have a very cool perforated texture/look. The other pieces he just liked - a more straightforward off-white gloss. Also, I really like the lower middle dash pieces which the off-white interior style offers (and no other).
As for pictures - I found autotrader to be a great resource. Narrow down the MINI search criteria then keyword for 'off-white'. You'll get some false positives but it should point you at dealerships that have a MINI w/off-white for sale. Then go to the dealership's website and look at the (usually) better pictures.