My tounge has a white coating and its a bit yellow in the middle but not that yellow jusy little is this normal?

Can be normal: Having a coating on your tongue can be a normal occurrance. The papillae(taste buds) can overgrow and pick up numerous stain dependent on diet, medication, and habits, like smoking. It is recommended that you brush or use tongue scraper to reduce this layer and film. This film on tongue can lead to bad breath.

Tongue scraper: Most people should use a tongue scraper (available at most pharmacies and supermarkets) once daily to help keep their tongues clean and free from coatings. It should be part of daily oral hygiene in addition to tooth brushing and flossing. Also have your own dentist take a look just to make sure everything is normal. From what you describe, it probably is.