I had a tonsillectomy as a child but half my left tonsil was left in. it hypertrophied over the years and i get frequent sore throats, worth removing?

Not necessarily: The problem in kids comes when the tonsils grow faster than they do, between birth & 8, with recurrent infections and sleep apnea making the removal common. If you are an adult, it might help sleep apnea, if present, but would not end throat infections. There is always tissue left behind that can be invaded by strep/viruses.A consultation with an ENT could clear this up.