I'm not an examiner, but an instructor.
I'd be extremely surprised if any examiner cared much what method and tools you used for airbourne diversion planning so long as
1) it didn't affect your ability to fly the plane safely and keep a lookout while you were doing it and
2) it produces appropriately accurate results.
For my own students I would advise them (quite strongly) against using either a wizz wheel or an electronic wotsit to do the sums when airbourne because they both would require enough manual skill to operate that the flying of the aeroplane and keeping a lookout is likely to suffer too much. Either should produce an answer that is much much more accurate than is needed and I would always teach to use a "rule of thumb" method based on some fairly easy mental arithmetic. That way they can carry on looking out the window while they're doing the simple sums in their head.
There's loads of different rule of thumb methods, all of which would produce results which are plenty accurate enough - I suggest that you discuss this with your instructor to find one that you both agree is OK for you.
You don't need to be 100% accurate with this stuff - the wind won't be exactly what was forecast and I bet you can't fly 100% accurately in a light single anyway - I certainly can't. The important thing is to get something that's fairly accurate and then have some method for correcting any errors. Again, a track error correction method is something that you should agree with your own instructor - there's lots of them.
Hope that helps a bit.