Making a kitchen worktop

[Nelly111s]

I'm making a kitchen worktop in olive - finished size 20mm thick. I'll be making it from probably 75mm staves, with loose tongues (20mm x 6mm) to joint the staves. I'm not sure if I should use an edge jointing cutter on the end grain, or loose tongues again. It's a straight 2.5m run, no joints. I think I'll need a batton at points underneath to help it stay flat and finishing with either 1101 or Top Oil. My plan is to make the top in two 325mm halves, slightly thicker than 20mm, then I can thickness and sand down to 20mm, before jointing the two halves as a 2.5m run.
Has anyone (especially those who are used to fitting them) got any tips (apart from "don't") for construction?