In some places when i zoom in on google earth, it is just a blur but some places are really clear, why? and how do i make it all clear?

Example of clear:

Example of blury:

Because the image taken of that area turned out blurry . I doubt there is much you can do.

Well it depends on what resolution the images are available in for the specified area.
If there aren't any higher resolution satellite images available, you can't view them.

well somtime's i have too wait a few seconds and it clears up but some places the pictures arnt always as good a quality as others.

Actually this is because either they havent taken any hi-res pics of that place or you havnt downloaded them yet. Thats usually the terrain (terrain google earth sets if it hasn't downloaded anything)

This happens to me in a lot of places in england, or did until around a month ago :\ nothing you can do

There are two main reasons behind this
1) The images are taken from satellites... there might be some obstruction like clouds
2) Some countries(like India) only allow blurred images to be uploaded to respect the country's privacy and not making tasks easier for terrorists .

sometimes they mess up and have hi-res photos of absolutely nothing

Empty Ocean Patch