It is OK. You could drop "away", so just "from here" is fine. Also, there are different guides for writing numbers. I spell out all the numbers that are pronounced as one word (0-20, 30, 40...) up to a hundred or so. Some guides recommmend spelling out only numbers 1-9, another says all from 1 to 99. Either way, it seems that it's proper to spell out small numbers, so it would be: "The Valley of the Shadows is about nine miles from here through the forest."

How to use the phrase “miles away from” in real life: A man asked his doctor how he could lose weight. His doctor told him to run five miles (about 8 km.) every day, for 30 days, and he would lose 10 pounds (about 4.5 kilos). So every day for 30 days the man ran five miles. At the end of the 30 days, the man phoned his doctor and said, “Doctor, thank you for your advice. I’ve run five miles every day for 30 days, and I’ve lost 10 pounds, just as you said I would.” The doctor replied, “That’s wonderful news. But did you have any problems running so much?” And the man answered, “Just one problem – I’m 150 miles away from home!”

Yes, '9 miles away from here' is fine.

The Valley of Shadow is 9 miles away from the forest.