Hiya PinkFizz,
I had one about 4 weeks ago and was absolutely dreading it! I can honestly say it was nowhere near as bad as i thought it would be. I had the spray and sedation, i remember every little thing about it, the sedation just took my nerves away for me, stopped me from panicking. I wretched a fair bit but they helped me concentrate on my breathing and that eased the wretching. Only when they got as far as my duodenum did the gagging start again but it was almost over by then anyway! It's uncomfortable but in no way painful, so please don't worry.
I had to wait for about 40mins afterwards and once i'd managed a cup of tea and a few biscuits i was allowed to leave, but only if i was accompanied back as i'd had the sedation, even though i felt fine, no drowsiness at any point. I had a slightly sore throat in the evening but it didn't stop me having some dinner.
I just hope they find out what's wrong with you so you can get treatement asap. They were able to tell me so much about what was wrong with me straight away and all i had to wait for were the results from the biopsies. You'll be fine, nervous but fine!
Good luck x