Can I take valium and rescue remedy together?

So I'm flying to chicago on Wednesday (volcanic ash permitting) and I've been given Valium by my doctor - I tried it and it didn't calm me much, it just made me drowsy but I also felt kinda weird. I've also tried Rescue Remedy, which calms me really well but doesn't last that long and doesn't send me to sleep. I'm just wondering if it's okay to take them together (or within hours of each other) without them being harmful? I was guessing that as RR is herbal it shouldn't be a problem, but thought I'd check.