  The discovery of different phases as a result of correlations, especially in
low-dimensional materials, has been always an exciting and fundamental subject
of research. Recent experiments on twisted bilayer graphene have revealed
reentrant unconventional superconductivity as a function of doping as well as a
Mott-like insulating phase when the two layers are twisted with respect to each
other at certain "magic" angles for doping corresponding to two particles per
moire unit cell. In this work we propose a microscopic model that takes into
account interactions and the van Hove singularities in the density of states of
the twisted bilayer graphene at doping corresponding to one particle ($\nu$ =1)
per moir\'{e} unit cell and study how superconductivity emerges. We identify
the possible symmetry of the order parameter as $s^{\pm}$, while if the
inter-valley coupling is negligible the symmetry is $s^{++}$. In addition, we
find and characterise the insulating region of the system, as a region with a
uniform charge instability where there is coexistence of the metallic and
insulating phases.
