I presume you mean that when you stand by the house and look down the garden you are facing East. That means that the trees are shading the garden from the rising sun and the house from the setting sun?
Until you actually watch the suns progress across the garden for a day it is hard to say how much light there is in a garden.
The patchy grass could as well be from poor soil, tree roots, compaction from over use etc, as lack of light.

That's nice of you to answer, thank you. Yes standing back to house, looking down the garden, is looking East; there are tall trees at the end of the garden. Having watch the sun's passage over the property yet. On balance, and from what I am reading on the subject, the garden will be warm and somewhat sunny in the am, then the shadows begin to grow and the cool will set in. Might rethink the purchase....thanks again

My back garden faces East too,Larastaxi..but with getting the sun from the south ,at the right hand side as well,I get sun most of the day,especially in summer .....sometimes a bit of shade is a good thing..but as Owdboggy says there could be other factors concerned,as to why the grass is patchy ..

Thank you Bloomer, nice of you to reply.

Depends how tall those trees are, really - if they're very tall, they will block the rising sun - but once it comes up above them in summer, you should have full sun till around lunchtime or just after. In the winter, you may get some early morning dappled sun if the trees are deciduous, with a shorter length of daytime when you have sun because of its being lower in the sky.
Part sun part shade is ideal for a huge number of plants, so there should be no difficulty with that.

As long as there is nothing tall to the south you should get lots of sun in the middle of the day, and later depending on the height of the house. Our mature sycamores throw a long shadow in the morning but it has gone by early afternoon and so there is a good semi shaded area that lots of plants will enjoy. Herbaceous perennials are usually dormant during the time when the shadow is longest anyway. And you will have a nice big area to grow things like camellias and magnolia stellata that need to be out of the early morning sun in frosty weather.

my front garden faces east and the border infront of the house gts lots of sun until about 1pm [summer] and semi shade after that. I grow lots of lovely plants here.

what sort of trees are there? will the belong to you or a neighbour? if yours when you buy you could trim/remove them.