Hi Claire,
First, welcome to OCF. I'm glad you found this site so early in your treatment. Your story sounds just like mine...sore on my tongue and the dentist sent me to the oral surgeon and the rest is history. I was 27.
I can't lie...you will be in pain. I never had any lymph nodes removed so I can't speak to that but the partial glossectomy (I'm assuming that is what they are doing?) is painful. I would suggest to buy plenty of soft foods and Ensure. It is important to get calories so you can heal properly..I made that mistake once and it wasn't fun. I have had 4 partial glossectomies...
About the surgery..I know you are nervous. Try to remember this is what these people do everyday. In my experience the doctors and nurses are so kind and will put you at ease..hang in there and keep us posted:)
((((hugs)))