Waking up with dry mouth, mucus in throat and blocked nose. allergy related?

Could be: If this is an ongoing or recurrent problem then allergy is possible. If it's quite new then infection is more likely especially at this time of year. Your doctor would take factors like duration, family history, exposures, physical findings and more into account to make a diagnosis.

Yes it is allergy: you probably have chronic sinusitis you benefit if you keep steam vaporiser by your bed. maybe starting an antihistamine. if persists you may need to be seen and start on a 2 week coarse of antibiotics make sure you start on saline nasal spray every 8 hrs

A viral infection: Your question suggests that the problem is of very recent onset and thus more likely from a viral infection. If this has been a chronic issue, then one would need to consider an allergic basis. Allergy is often associated with itching but a cold is not. Also fever is not present in allergy.