Hello there. I was induced with DC1 at 3cm (my waters had gone very early, so they wanted him out quick to minimise risk of induction).
As you are 3cm already, I doubt very much you'll have the pessary. As others have said, it'll be waters broken and then if that doesn't work, the drip.
As your body is already on its way, so to speak, chances are your induction will be successful. I say that from experience and as the thought of being induced was, for me, terrifying.
My induction was fine. 9 hours, gas and air, one shot of pethidine. No other intervention and a slight graze only - so inductions CAN be OK and not neccessarily lead to epidural, episitomy, ventouse etc. The pain, I found, was manageable, although I have nothing to compare it to as DS was my first.
What I would suggest is:
- You argue very strongly NOT to be confined to bed. Some hospitals try and keep you on your back in bed due to the need (if on a drip) to be continuously monitored. I refused, and spent my labour on all fours, leaning over the bed (even delivered standing up!). I could not have managed the pain otherwise and lucikly my midwives supported me. Please do insist on this if you want it as I'm pretty sure, for me, it led to an OK labour/delivery.
- Find out as much as possible beforehand what will be happening to you. Not easy, I know - no one told me at my hospital until I kicked up a fuss! But knowing exactly what the process was, what might/could /'go wrong' (e.g. at what point they would intervene if I didn't progress) and even where they would put me really helped me cope with being, frankly, shit scared about the whole thing.
Inductions can be OK and it sounds like you're off to a good start. Whatever happens, you'll have your baby very soon - best of luck.
ps. I'm currently 6 days overdue so facing up to the same thing AGAIN so know how you feel! 
pps. you don't have to be induced if you don't want to, or want to give it a few more days. You can have expectant monitoring instead - they like to push you into induction rather than this and at my hospital they're not even talking about induction until 40+12 for me...