There is no "standard" health and safety position.  Health and safety roles are many and varied both across and within sectors.

My only knowledge of railway requirements relates to Network Rail, who are responsible for the tracks.  It is subcontractors who do the actual track maintenance, but Network Rail write the rules.  And do they ever write rules.

There is an elaborate and prescriptive set of procedures and rules and processes aimed at ensuring the safety of track workers, as well as the effective and safe functioning of the railway infrastructure.  So this is a more prescriptive (less flexible) working environment than in most sectors, with a lot of emphasis on following the requirements.  For this reason, experience in the sector is an important criterion for recruiters, which I've seen in each of the handful of job adverts and specifications for rail-related H&S jobs that I've seen.  I don't see it as being easy to break in to from outside.

Environment and sustainability are also big issues for Network Rail (as a public sector body) and often considered alongside the H&S requirements.

There are even specialist rail consultancies who service rail subcontractors who may not have the necessary in-house expertise to understand or meet Network Rail requirements.

Network Rail have a website called "Safety Central" where their expectations for safe working on the railway are described.  It's not a case of the poor old H&S person keeping everyone safe, it's very much a team and individual accountability.

It really is mainly about safety rather than health, with health (except when it impacts on safety) getting only a little of the attention.  That is because their nightmare is workers being hit by trains.

By the way, Karan, you don't have to target a particular sector to work in.  You can search for opportunities across sectors.  You are probably most likely to succeed in a sector in which you do have some experience of working in some capacity.