In standard doses is it safe to take these together? milk thistle, selenium, alpha lipoic acid, magnesium, potassium + b complex? on benzos sometimes

Probably ok ...: They are few if any studies evaluating whether specific herbs/supplements can be taken together. A rule of thumb: a large dose of anything should be taken at a separate time as it may compete for another's absorption. There are reports of supplements interfering with benzodiazepine withdrawal, but occasional use shouldn't be a factor. Careful with those, though! They're addicting!