Every night I wake up twice as my bladder is full and I have to go to the toilet. I don't drink a lot of liquids so I'm concerned that this isn't normal?
Getting up once at night is considered to be within normal limits. If you get up more than once it is worth discussing with your GP.
There are a number of different things that can cause this. Some are common and some are rare. The kind of things to consider are lifestyle e.g. how much fluid is taken including tea and coffee, and the presence of other co-existing illnesses such as diabetes or heart failure.
Also certain conditions affecting the lower urinary tract - such as prostate abnormalities in men - can sometimes cause this symptom. Certain medicines can cause it, for example, tablets to manage water balance.
It would be a good idea to speak to your GP who can take a more detailed history. The presence of any associated back pain or difficulty walking would be a reason to see your GP urgently.