Just to reply,
I have settled on the CASIO MX-8B calculator I bought from Wilko's last weekend, its great! and if I can't use it they offer students one to use of their own anyway, so no worries.
To answer question to 'DIGIT', you aren't allowed to take materials/paper/possessions with you into the Pearson exam room, but you are given whiteboard pieces of A4 Sheet (more than 5+ sheets) with whiteboard marker felt-tip pens to work out calculations with.
I found this page helpful to print off it contains most of the information...
I also highly recommend doing the 'bookkeepers.org.uk' BA7 mocks (both), as they really helped me understand the tricks in questions being asked and have made me feel a lot more relaxed/prepared.
Next week is my exam!