I'm going away for a month, no internet. Is there a way to safeguard my sanctuary, or must I just risk..

Here is no way to shield it or protect it for that length of time. If you are in an alliance then let them know and try to move your base to the middle of alliance territory, if it is surrounded by friendly bases then it makes it harder for others to attack. If you cannot do this then move it to a quiet location far from the center.

Try to use up any spare resources by starting upgrades / research before you go.

You may well get attacked but when you return it will just be a case of healing or re training troops.