Hi all and thankyou all so much for your replies.
Its a while since I asked for your advice & tbh, I've been doing so much research & joined so many forums/groups that I'd forgotten which one's I'd posted on, hence my very delayed thanks.
Anyway...update: We finally booked a taster cruise yesterday to the Fjords next May on Iona. (I think the world cruise will be many more short cruises away before we make that leap!).
We wanted to make our first time really special so opted to splash out on a suite. We chose the Select option & picked the Arafura Suite 10110 deck 10. I umm'd & ahhh'd over fwd or aft after doing loads of review searching, purely basing our decision on the location which seemed better for us as far as facilities we think we'd like are concerned. Woke up last night in a panic thinking we should've booked aft (think wind on sea days) so I've just spent over an hour on hold to P&O to change position but unfortunately....the aft (corner) suites are all gone so we're sticking with our original choice. Really helpful lady though so made the wait time worth it (I guess). Just a shame you can't manage this sort of thing online.
So much still to learn. Thanks so much again for all your replies & tips.
Lisa