My gp says i have laryngitis caused by a viral infection but since seeing him i seem to be coughing up more phlegm some with tinges of blood?

Viral infection: Viral illnesses typically evolve over time-so you don't see all the symptoms all at once. What you are describing could be apart of the viral exanthem. If your symptoms don't start to improve over the next 48-72h then go back to see your doctor. Viruses can often leave you more susceptible for bacterial infections.

Inflammation: You likely have post viral laryngo-tracheobronchitis causing cough with phlegm usually clear but may be blood tinged. A chest x-ray mae be required if the symptoms persist. The usual therapy id steroids and narcotic cough suppression. If not improving a bronchoscopy may be needed. Also if smoking one should stop.