Running

Got 16miles tomorrow, will be my longest run to date. Suffered last week by just grinding to a halt with lack of energy at 13miles. Should a gel halfway round sort me out or is it a little more complicated than that?

Give it a go!

Drinks are generally easier to digest, so if you've only been drinking water to date I'd try a lucozade or powerade first...

I'd get used to using them asap, so yeah, and its a good time to work out which ones you like.
In my (limited) experience, you'll find it makes a massive amount of difference.
Good luck.
First step up in distance for me too this weekend, though in reality, not very far (11miles), its been too long coming...
Having swapped training goals for triathlons this year, I may enter a late year marathon, just to get a GFA time/ I want that sub 3hr. It annoys me still.