  The European Pulsar Timing Array (EPTA) network is a collaboration between
the five largest radio telescopes in Europe aiming to study the astrophysics of
millisecond pulsars and to detect cosmological gravitational waves in the
nano-Hertz regime. The advantages and techniques of handling the
multi-telescope datasets of a number of sources will be presented. In addition,
the results of the EPTA timing analysis of the pulsar-white dwarf binary PSR
J1012+5307 will be reported. Specifically, the measurements for the first time
for this system, of the parallax, the variation of the projected semi-major
axis and of the orbital period. Finally, the derived stringent, theory
independent limits on alternative theories of gravity, with the use of this
ideal laboratory for strong- field gravity tests, will be presented.
