I used TENS, then G&A also for my first, once they gave me Synto i begged for Diamorphine, which made me more drowsy and out of it, don't recall any significant pain relief.... ended up with emCS
Second birth, again TENS and then G&A later on, had a bit of a panic, was struggling with CFM and getting positions changed, ended up with Diamorphine although had been dead against it. Regret it, was drowsy and compliant and out of it.
Next time will have a Doula and stay at home! Don't want to interfere with body's natural hormones etc! That's my pesonal opinion now that I've learned more about childbirth. It will be HARD but interfering tends to lead to more interfering and longer births so plan to at least TRY at home, realistically know that it may not be as easy as all that!
Cutting a long waffle short, I don't recommend diamorphine from personal experience, but then I cannot live with the risks involved in epidural and would never consider that either.
It's important to research your pain relief options fully, all pros and cons, and make an informed choice.