Lichen on bark

We have inherited in our new garden a Ginkgo Biloba Tree. It has apparently been growing there for at least 15 years. It sits at the bottom of the garden in Northern France facing South. The tree is not a very good looking specimen and has a lot of lichen on the bark.We would like to improve the quality of this unusual tree. Should we attempt to wash off the lichen and can we feed the area in which it grows?

Question by David and June Smith.