I have had a partial upper denture for about four years. I only have four of my own upper teeth so the denture attaches to two of them with little metal clips. It covers the roof of my mouth and the clips don't show, but they hold the denture very firmly, no wobbling.
To begin with it will feel huge and very strange in your mouth, and you may find some words difficult to pronounce. Don't worry, just persevere, it will get better. Try singing along to the radio or reciting nursery rhymes, it helps. If your denture should feel at all loose or uncomfortable go back to your dentist it may need a slight adjustment. You should not need to use denture fixative. I bought some, just in case, and tried it once. It sticks like superglue! I thought I'd never get my denture out again.
Over the first few months your denture will 'bed in' to the shape of your mouth and gradually feel less alien. I was advised to remove my denture at night, but I do actually wear it all night as I hate waking up without it. Because it clips to my teeth there is no risk of me swallowing it!
Obviously thorough cleaning is essential and your dentist will advise on that. I use a soft toothbrush and regular toothpaste for daily cleaning and the fizzy tablets twice a week to sterilise. I can eat all the foods I would normally eat and bite into apples and carrots etc., but I avoid toffees and sticks of rock! Tiny food particles will slip under the plate sometimes but are easily rinsed away wherever you are.
Having my denture fitted is the best thing I ever did. I'm no longer embarrassed about my teeth and can smile and laugh with confidence. And most importantly I now have a healthy mouth. I will probably need a partial bottom denture in the future but it holds no fears for me now.
I know it's a worrying experience for you, but it really won't be as bad as you imagine. Good luck.