  We investigate a scale-invariant $B-L$ scenario where the Standard Model (SM)
is supplemented with a dark scalar $\phi$ which has gauge \& Yukawa
interactions, with the couplings $g_{BL}$ and $y$, respectively, leading to
radiative plateau inflation at scale $\phi=M$ in the ultraviolet (UV), while
dynamically generating the Electroweak and Seesaw scales \textit{\'a l\'a}
Coleman-Weinberg in the infrared (IR). This is particularly achieved by
implementing threshold corrections at an energy scale $\mu_T$ arising due to
the presence of vector-like fermions. We show that implementing the
inflationary observables makes the couplings solely dependent on the plateau
scale $M$, leaving us with only two independent parameters $M$ and $\mu_T$.
Within the theoretically consistent parameter space defined by $m_{Z_{BL}} >
850~\rm GeV$, from the assumption of independent evolution of the dark sector
couplings from the SM couplings and $M < 5.67~M_P$ required for the realisation
of inflationary \textit{plateau-like} behaviour of the potential around
$\phi=M$, where $M_P=2.4\times10^{18}$ GeV is the reduced Planck mass, we
identify the parameter space that is excluded by the current LHC results from
the search for the heavy $Z_{BL}$ boson. For typical benchmark points in the
viable parameter regions, we estimate the reheating temperature to be
$\mathcal{O}(TeV)$ thus consistent with the standard Big Bang Nucleosynthesis
(BBN) constraints. For typical benchmark points ($M=5.67,~1,~0.1~M_P$) we
predict the scales of inflation to be $\mathcal{H}_{inf}=2.79\times10^{12}$
GeV, $1.53\times10^{10}$ GeV and $1.53\times10^7$ GeV, respectively.
