Take Toilet roll!! On previous trips, the toilet tent always had a roll in there, but on this trip it did not. Toilet roll became a bit like gold dust and became a barter material! So yes - don't forget to pack plenty.
Be prepared to be a bit shocked by what you find behind most rocks and boulders on the trail - other people obviously haven't waited to find a toilet!
Also - take a small scarf to tie over your mouth on the dusty paths. It may have been due to the time of year (with the scree not being frozen), but the clouds of dust kicked up by those in front on the summit day descent in particular, left me with a cough for a week after we got home.
Make sure you are as fit as possible before you go - the last thing you want is to be worried about acheing legs when you can't catch your breath. Also - consider taking a general antibiotic with you. 2 of us on the trip benefitted from this when we had stomach upsets.
I would say take iodine with you- lower down, the water was purified by the leader with something that smelt like chlorine - but as I understand it, this doesn't kill everything. When we asked if it had been boiled, it turns out no - they had purified it lower down as it was 'stagnant' water (nice). But higher up where the water was free flowing- they would boil it! Seems the wrong way round to me! Anyway - I put iodine in it all - but recommend neutralisers and maybe Berocca to take any remaining taste away.
Don't be lulled into a false sense of security by the first few days easy walking round the Shira Plateu. Although there are some longer days as the trip progresses - the summit day is still a bit of a shock to the system. It took us a long 6 hours at -5 degrees in the dark to Stella point, another hour to Uhuru peak (this last bit is easy compared to getting to Stella Point), then 2 and a half hours back to Barafu camp. After a break - it was another couple of hours to Millenum Camp (but they sell beer!). Its a nice camp with trees around but very dusty - but as I said...they sell beer!
Also - we were not expecting a 6 hour walk the last day to get back to the pick up point. The trip notes hadn't mentioned how long it would be. It was very pretty in the forest - but a long and rushed descent.
Basically - it was an excellent trek - the glaciers on the top were amazing - the scenery is so barren and rugged and dramatic. The Baranco wall is very imposing and looks so hard - but actually it was quite fun scrambling up parts of it, and it is in an area you actually see plants!
As long as you are pretty fit and aware of the joys of sleeping in tents and roughing it a bit, I would highly recommend this trip!