Hi mormor,
My soil is non-chalky pH7 and I have a blueberry bed that I prepared before planting them out with the addition of some sulphur chips and ericaceous compost at the start. Despite being told over and over again that pine needles are not particularly acidic I have gone and collected a pine forest mulch every year to top dress with (I also add a little yellow sulphur) - and my blueberries seem to be thriving. Even if it doesn't particularly help with the pH, the pine needles break down to a really lovely dark rich compost layer on the top after a couple of years.
Squeezy