I've had conscious sedation twice - the latest was last Saturday, when I had an impacted wisdom tooth removed.
On both occasions, it was fantastic (and this was on the NHS, so don't worry if you're not a private patient).
The worst thing for me was having my blood pressure taken (have a weirdy phobia of that) - everything else was a doddle. I felt utterly calm, disconnected and yet not out of control - I realise that doesn't make much sense but it's the only way I can describe it. I remember bits about it, but it felt like it lasted for a few minutes when it was actually about 45.
Although I can't remember what I was talking about, I do recall having a conversation with the dental nurses before and after the procedure. I was probably being a bit of a twat, to be honest, as I was trying to convince the dentist he had no knowledge about breastfeeding...but that's another story 
Seriously, they are used to dealing with anxious patients - you will be fine. I was nervous the first time because I didn't know what to expect and it was all marvellous, the drugs were FANTASTIC, it was GREAT (as I announced to the entire waiting room on my way out of the surgery, much to DH's amusement).
You do need to take it easy afterwards as you can feel a bit shakey. I had a nap when I got home and was fine.
Hope this all reassures you. Please don't worry - I am a big wuss and I was completely fine.