Forgot to say, that distance, think about a rack and pannier, I find it much comfier. Carry a waterproof jacket, spare batteries or back up lights, 2 tubes and tyre levers pump etc. Make sure the person you will need to come and rescue you in the event of a disaster knows your route.
I have a banana and coffee before my commute (12 miles each way, 3 times a week usually) and breakfast at my desk. I eat a lot anyway, but I find something carby an hour or so before heading home helps. I also carry an energy gel for emergencies - sometimes at the end of the week I have resorted to using one. Or stopping at the ice cream van at Bramcote Hills Park....
I'm never sure about carrying a drink - usually only in the summer when it is proper warm, but there are times when hydration has been over done and hedges are required.
And definitely recce the route at the weekend, you don't want to be figuring it out in the rain and dark at 7am next Monday morning.
Good luck, let us know how it goes.