Onemoremile
I used lucozade sport last year, and have been using it this year too. I had a problem a few week ago, when I made the mistake of washing my energy gels down with it. That gave me bad stomach cramps for hours after.
However, Now I mainly just drink lucozade sport. got through 2 pouches of it and a bit of water on my 20 miler today with no probs. Ate energy bar half way round. I have heard of many people though who do suffer probs with it. I suppose its a matter of finding what suits you, after all this time luc sport obviously doesnt. I'm no expert , but you'll need some source of extra energy on the day. have you tried gels? High5 are good, and I like the taste, also their energy bars are nice.
Good luck and I hope you find something to suit. and all the best for 13/04