Well, here's how my story ends:
As I said in my first post, Apple were great about sending out a replacement. They were apologetic and arranged the whole thing in around 20 mins. I made the call asking for a replacement on 5th November, my original MacBook was collected yesterday (10th November) and the replacement arrived today (11th November). I though that was quite a quick turn-around so was pretty pleased
So, this morning I took the delivery, opened the box and looked for wonky keys right away! They were straight

- here's a comparison:
Original MacBook:
My Replacement:
Now, admittedly, if you look
real close you could say they're not 100% in-line, but to the naked eye - they're perfect!
Secondly, I checked the battery case. Unfortunately, this was a little disappointing. Where I'd gained straight keys - I'd lost my snug battery case. This one rattles, it's not snug at all - it really sits incorrectly in one corner of the case...
At first I thought it just wasn't pushed in correctly - but no, that's actually how it was sitting. However, unlike with the keys, I was prepared to flex the battery case. Doing so transformed the above into this:
Now, you can still see that it's not totally in line but the case no longer rattles, if you apply pressure to that corner it no longer moves and makes a tapping noise as it did - so I'm happy! Also of course, the battery cover is replacable - so all is good!
I'm now happy, and can't wait to use it properly on 25th
