I had my tonsils out aged 19. The consultant was horrified that they'd been left so long, and said they were the worst he'd ever seen in a thirty year career.
I'm not going to lie - recovery took ages and was pretty grim, because despite doing everything right (mouthwashing with salty water, eating hard foods) I got an infection and hemorrhaged - BUT:
Once I did begin to recover, I felt a million dollars - I used to get endless throat / chest infections and was constantly on antibiotics, (which give me diarrhea anyway - joyous!) I got every cold going and was always run down, with mouth ulcers and dry flaky skin - basically I looked and felt like shite most of the time.
Post-op, all that went away and in the 16 years since I've hardly ever been ill.
Also: don't underestimate the damage tonsillitis can do to other areas of your body. I've had two subsequent operations since the tonsillectomy - one to remove my adenoids and then a sinus op. The repeated infections from my throat over the years had travelled upwards and scarred these areas badly, leaving me with chronic sinus problems and a permanently snotty nose / catarrh.
Get the little feckers whipped out! You will have two weeks of feeling truly grim, I'm not going to lie to you, but then after that you'll see the difference to your general health more or less straight away.
But please - don't cancel! They don't generally do a tonsillectomy on an adult these days unless you really do need it.
All the best.
x