Hi Darragh,
I used 2 x bottle cages for liquids one on the aerobars and one on the downtube, I had a cage and bracket behind the saddle to carry my spares/mini pump CO2. I taped Gels to the toptube too.
I also put on a jersey for the 1st lap of the bike with more nutrition and a small bottle of water which I discarded soon after. (A wonderful German couple actually took it from me and gave it back to me as I entered the finishing Stadium)
Check out the distance between Aid Stations and what products they have and also if they agree with you! And practice in training your nutrition and also how to change a punture/use Co2.
Casso