Grandis is the red hardwood that is used by joiners for stable knot free wood. The pine from B&Q is not that bad for softwood (pine), generally it's being stored at around room temperature as well. There's no silver bullet, you have to drive around and places and be prepared to leave it if it doesn't check out. Look carefully at every piece you buy and be prepared to stand your ground. Places don't like you cherry picking but it's not worth letting them sell you rubbish.
Grandis is the red hardwood that is used by joiners for stable knot free wood. The pine from B&Q is not that bad for softwood (pine), generally it's being stored at around room temperature as well. There's no silver bullet, you have to drive around and places and be prepared to leave it if it doesn't check out. Look carefully at every piece you buy and be prepared to stand your ground. Places don't like you cherry picking but it's not worth letting them sell you rubbish.
You can go to a joiner but it will be expensive.