You can use any calculator in the world (including Excel) to work out P[Z< number]. You do not need to use a printed table and linearly interpolate.
However, for Paper A, I would be cautious to show my working if the number was negative, for example, P[Z< -0.543] = 1 - P[Z<0.543] and then use Excel. I would also not use ANY Excel s/sheet where I had typed anything at all before the exam clock has started.
Weirdly, if you use a Casio (fx991-ES for example), the phi function is already in the circuit board, which is equivalent to having an Excel s/sheet ready set-up with just cell B1 saying "=norm.s.dist(a1,true)", ie ready to type 0.543 into Cell A1 and give an answer in B1. Yet, my understanding is that this second method would constitute a "pre-existing spreadsheet" - so you're actually better off with a Casio in this respect - a pre-existing calculator, I suppose :-D
Good luck!
John