Hi! I was exactly like you, first smear and was not expecting an abnormal result at all! I cried for about 2 days and couldn't stop googling (bad idea!). Like you my appointment was very quick (I got the results 5 days after my smear and the colposcopy was booked for the following week). I was a nervous wreck by the time I went in (having to wait over an hour after my appointment time didn't help!) but honestly it wasn't that bad. My consultant and the nurse there weren't very friendly but even with that added stress I still managed to hold it together! It's similar to a smear, but you lie down on a couch with these special rests for your legs so you end up in a very undignified position and there's a camera focused on your bits (I found this funny to be honest, a magnified image of your fanny is a strange thing to see!). Then the doctor inserted a speculum like with a normal smear and dabbed some fluid onto my cervix (felt cold but not painful). Then he could see some abnormal areas and decided to take a biopsy using local anaesthetic. The injection felt like a quick pain but then I felt nothing, they put a sticky pad on my leg and turned on this noisy machine then within 30 seconds they had finished. I was given privacy to get dressed and the nurse gave me a pad. The doctor said it was likely I'd need treatment but they wanted to make absolutely sure before they went cutting more bits off my cervix! I was very worried but he reassured me it was very common and it would take "maybe 10 years" for this to become cancer. I received my biopsy results in 2 weeks and I've got a LLETZ on the 2nd March.
I know it's hard but try not to read horror stories. My boyfriend gave me some good advice and said the only reason there are so many bad experiences is because most people who have these types of abnormalities get treated and are fine and have no need to post their story on the Internet. It's a very small minority you read about :) best of luck, you'll be fine!