Looks like 1922 pattern tunic to me and therefore post WW1. If I remember correctly, these are distinguished from WW1 issue by there khaki rather than white linings. I suspect the cap is also later, due to the absence of stitching on the brim. Others may correct me however. The tunic is probably genuine, cant say about the rest, better pictures would be needed.
A bit of a puzzle here. The cap is certainly postwar judging from the large peak, but the tunic looks WW1 from the outside and has the correct two collar pleats. It could be a 1918 transitional variant, but it's impossible to say with these pictures. An overall view of the inside would be good. Is the label in the tunic, or in the trousers?
This is an OTC tunic modelled on the 02 pattern. most have commercial tailors labels. The cap does look post WW1 but difficult to say without internal shots of the lining. It is not re-enator stuff. If the jacket has two pleats under the collar it follows the WW1 standard tunic pattern. All up £2-400.