Use the powders you have, or are locally available. Here in the US a lot of us use Hodgdon Varget or Reloder 15 for the .308, but they're easily available. I couldn't tell you how far I'd have to drive to buy a pound of VV powder locally. It's not something we see much of. However, I find this chart useful
when I'm comparing powders. It's produced by ADI, the Australian powder manufacturer. Based on that chart alone, I'd probably try VV-N140 in the .308, based purely on it's position in the chart.
If we go to the Hodgdon Burn Rate chart
, we see VV N140 directly between Reloder 15 and H-Varget. I'd feel very comfortable loading that powder in the .308. However, VV-N135 isn't much faster, more in the realm of 4895, which is a powder I'm familiar with and use a lot of. N135 might do better with bullets in the 150 grain class. You'll have to let your rifle tell you what it likes, but I don't think you'll go wrong with a pound of N135.