Wouldn't waste £40 going from 3000 to 3200 RAM, you won't see more then a couple of percent increase, and you'll want to get better timings not faster MHz
Yeah 3000 with decent timings seems to be the sweet spot (though prices have come down a bit this week so might be worth checking) - 3200 is often a big increase in price for pretty much negligible performance on the 2600 - though the higher models with overclocking and gaming in mind still benefit.
EDIT: Though it could be worth it possibly with a future CPU upgrade on the same motherboard in mind as RAM prices are all over the place like crazy.