Best thing in Lorient is to match the escorts speed, but stay at least 200 meters behind it. That way you won't cause it to run aground.
I've noticed that once at sea out of Lorient, and at the beginning of the channel, the escort can and will take off in different directions from the course you set for your Uboat. That's why it's always advisable to use the Minefiels/Subnet charts. Or at least remember where they are to stear clear of them. Once out in open waters you are on your own.
At Whilhelmshaven, the escort guides you all the way out past the nets and mines. Seems they're more thoughtful there of your Uboat and want to see you safe.