Completed the C2C three times including once East to West, wild camping.
Gaiters are a must, worn beneath over-trousers when raining.
I took 2 x 600ml bottles which was enough for me.
A single headtorch will suffice if not walking through the night, in which case a small spare would be handy. (only to assist changing batteries in main, if they suddenly go as mine does)
Remember, only take what you will need, try to avoid taking 'just in case' items, as carrying a too heavy sack (30kg+) soon spoils the enjoyment and becomes a burden. I abandoned my very 1st C2C due to carrying too much weight. Since I changed to going lightweight the route has never taken more than 5 days.