My left tonsil is bigger than my right. Has been for a couple of months. No other symptoms. Have seen GP about it. Is it normal to have one bigger?

Tonsillar asymmetry. A small degree of difference between the right and left tonsils is not necessarily unusual. You should see an ENT doctor to evaluate this. There are circumstances in which removal of your tonsils would be recommended. If there is a significant difference in size between your tonsils along with atypical appearance and texture of the enlarged tonsil, then removal may be warranted.