Gas and air didn't give me any pain relief .. It was more to help me breathe through the contractions. Some people feel spaced out or drunk but I didn't get any of that .. Everybody is different. I didn't have an epi so have no idea what it feels like but I have heard it slows labour down.
Def buy a gym ball .. I bounced everyday for 30mins from 36 weeks and it really helped to move the baby down. Also walk as much as you can in the last few weeks, again this helps baby move into position.
You will know when your contractions start .. You will prob get more pain in the last few weeks before baba comes, braxton hicks get stronger and I sometimes thought they were the start of labour but they just disappear. It's just instinct .. You know when labour starts.
Xxx