I would absolutely keep an open mind hun. These babies do what they want, how they want. And every labour is different as is how mum handles the pain.
I went in wanting everything available just in case, and my labour wasn't great (I won't tell you as I got really annoyed when I was pregnant with labour stories!) so I ended up having diamorphine very early on in my 9 hour labour. I found it really helped me as all I can really remember is asking the boyfriend to clean out the dinosaur pen and telling the midwife I'd fixed her car! Then it was time to push, which gas and air helped me fine with.
Just remember everyone is different, there is no right or wrong answer, everyone deals with pain differently. Do what you are happy with, but have an open mind that it may not go how you wish.
However it happens, there will be a lovely baby at the end, so keep thinking positive.