  The far-IR/sub-mm wavelength range contains a wealth of diagnostic
information that is important for understanding the role of radio AGN in galaxy
evolution. Here we present the results of Herschel PACS and SPIRE observations
of a complete sample of 46 powerful 2Jy radio AGN at intermediate redshifts
(0.05 < z < 0.7), which represent the deepest pointed observations of a major
sample of radio AGN undertaken by Herschel. In order to assess the importance
of non-thermal synchrotron emission at far-IR wavelengths, we also present new
APEX sub-mm and ALMA mm data. We find that the overall incidence of non-thermal
contamination in the PACS bands ($<$200$\mu$m) is in the range 28 -- 43%;
however, this rises to 30 -- 72% for wavelengths ($> $200$\mu$m) sampled by the
SPIRE instrument. Non-thermal contamination is strongest in objects with
compact CSS/GPS or extended FRI radio morphologies, and in those with type 1
optical spectra. Considering thermal dust emission, we find strong correlations
between the 100 and 160$\mu$m monochromatic luminosities and AGN power
indicators, providing further evidence that radiation from the AGN may be an
important heating source for the far-IR emitting dust. Clearly, AGN
contamination -- whether by the direct emission from synchrotron-emitting lobes
and cores, or via radiative heating of the cool dust -- needs to be carefully
considered when using the far-IR continuum to measure the star formation rates
in the host galaxies of radio AGN.
