Lets be honest - you will get caught up in the hype of the day and burn your candle too soon. Everyone does
Rather set yourself small achievable goals: example: stop at every 2nd (or 3rd) water point, or not at every water point. Or, you can stop on an uphill to catch a breather but your not allowed to walk - pedal only - even if you stop 2 or 3 times up the hill.
Know what your avergae pace is for a normal ride, lets say its 18kph. Then aim for a 16kph average speed for the race day to ensure you dont burn out too quickly
As for food, you'd be stupid to figure it out on the race day. Maybe a goo gel gives you the runs due to the sugar high, or an energybar is just too chewy to actually chew.
Prep now for what foods you want or need to carry. A good starting point is to figure out the food the next time you get on the bike for a long distance. A generl rule of thumb that most average Joe's do is about half a bar of sorts every 20km.
Foods that I carry is a banana 30min before the start, another one for during the race. I also carry good old dry wors sticks with me for quick protiens. I eat half a fast bar (the brand fast bar) every 20km or there abouts. So for a 100km ride I'll swallow 3 bars plus a banana plus some dry wors sticks. I dont do gels at all as they give me a sugar crash - if I have to use a gel then I use an Enduren pure honey gel specifically.
Just remember, foods wont give you superman powers, you also nedd to carry some fitness into the ride. If you cant ride daily, go for a run
Water is also important and I gulp it down, so I carry a Uswe 1.5lt hydration pack and 2 bottles. One of the bottles of water is mixed either with simple rehydrate, or with a Biogen Cytogen powered mix which replaces electolytes etc. You must know what your fluid usage is per 20km, that way you can guage how far you can go before you need to stop at a water point to fill up. If you dont, then budget on a bottle per 30km or less. In my case thats 100km before I need to refill
Keep a stash of cramp ease or good old Rennies for some cramp prevention. If you think you will get a cramp on the next climb, take some pills before the onset of the cramp. I use rennies and they work fine for me
Most of the foods you can get from your local dischem or clicks, so easy enough to source instead of going to a million bike shops
As for tactics, try figure out riders of similar fitness to you when the race starts, usually in your batch you will pick up riders of similar speeds to you. Its better to ride in a bunch (easier and less energy usage) than riding solo - so be on the look out for bunches to jump on to. You're not there to win, so there is no need to beat everyone on the first hill and kill your legs for the rest of the ride
Climbs - well, thats up to you. But its important to know the route before hand so you dont get a surprise when you come around a corner and see a monster to get over. If my legs are burning, then I change one gear up, if the lungs are burning, then one gear down. A good indicator is to not be out of breath when you talk during the climb, and if you are then perhaps tap off a bit to bring the heart rate down a fraction
Other than that have a blast, the gees is always lekker