Hello! Portam Hall would inform Astarion that the wagons are running again and roads are once more open, so he may simply use that to get to the mining camp. The trip will take approximately 1-2 days each way, depending on speed of travel. If he wishes to stay overnight, one of the families in the mining town would be happy to host him. Though their accommodations are not the most comfortable, they will greet him warmly.