There are two types of lorica segmentata that you might want to see. First, there are actual archaeological finds of the material (and here we might include Roman representations of this type of armour in sculpture). Then there are replicas or reconstructions, of the sort you might find in museums (a bit dull, but quite well-behaved) or being worn by re-enactors (much more lively, but can prove temperamental).
Finds
Many museums in Europe that have Roman military finds contain pieces of lorica segmentata. Amongst these, in Britain we can include the British Museum (finds from Hod Hill), the National Roman Legion Museum (Caerleon) and the National Museums Scotland (Newstead), the Museum of London (London), the site museum at Corbridge (the Corbridge Hoard), and the Great North Museum Hancock in Newcastle upon Tyne. In continental Europe, important collections are held in the Vindonissa Museum (CH), Kalkriese (D), Stuttgart Landesmuseum Württemberg (D), and the Carnuntum museum (AU).
Reconstructions
Two of H. Russell Robinson’s original reconstructions of Corbridge-type armour can be seen in the Legionary Museum at Caerleon (type C) and the Great North Museum Hancock (Type A) in Newcastle upon Tyne, whilst another is held by the Römisch-Germanisches Zentralmuseum Mainz (Type B). Other museums, such as the Grosvenor Museum at Chester have more recent replicas based upon Robinson’s original work.
To see some real people wearing lorica segmentata, talk to them, take photographs of them, find some re-enactors. Most will go to public displays and perform drill and show off their reconstructions, but many will also do smaller events and educational visits to schools. Locate a re-enactment group near you and find out where they are going to be performing.