In short - sometimes it is luck - being in the right place at the right time. Many list subscribers will have got their first job in OHN as a result of a training or screening post. The other option is to qualify as an OHN and gain SCPHN registration.
With regard to getting a job as a screening nurse - if you do not have them already gain a portfolio of screening skills eg spirometry, audiometry, HAVS. There are a number of courses advertised in the Occupational Health Journal. If you are a member of the RCN then they have it in the RCN library. If not an RCN member, I would strongly recommend subscribing. The publisher is Reed publishing - you can find them through Google.
Join one of the local OH groups - there has been info posted on their in the last few weeks - again a list of them is included in the OH Journal. If you are in commutable distance of London you could apply for our course at London South Bank University. You may be eligible for some exemptions if the units you have completed on your oH& S degree are transferable. This is the direct link to info about the LSBU course:
If you are not based close to London there are D/L courses available at Robert Gordon in Aberdeen or University of Western Scotland. The NMC can provide a list of institutions throughout the UK. Not all the courses which are validated are still running so it may involve a bit of detective work.
I hope this is helpful
Course Director Occupational Health Nursing
London South Bank University
OCC-HEALTH ARCHIVES: http://www.jiscmail.ac.uk/lists/occ-health.html
CONFERENCES AND STUDY DAYS: http://www.jiscmail.ac.uk/cgi-bin/filearea.cgi?LMGT1=OCC-HEALTH