I noticed this morning that the front 4 teeth have a white line at the bottom quarter of them. I am worried that this might be the start of my teeth's enamel eroding. Can you help? If it is what can I do? :(

The tooth enamel is thicker and more durable than you think. Are you having pain? What is your age?

If you only notice the white line in the morning it could be that you slept with your mouth open and the teeth have dried out. Give them some time to rehydrate and check them again. Usually erosion of the front teeth is subtle and noticed as a very smooth feeling behind the teeth.