What colour are the wires attached to your last light? Is your last light a pendant fitting with a shade? If so they are probably just a blue and brown one. If you unscrew the ceiling rose and look inside you will see other wires which should include the earth.
I suspect that you have to remove the ceiling rose altogether to install your new fitting. Be very careful to switch off the power and take note of what wires go where before you remove the rose to install the new fitting.
Have a look in the projects section as well where you will find lighting wiring diagrams.
It's common to find no Earth (CPC) in circuit on installations that are over 40 years old, because one they didn't fit them and two sometimes used metal conduit to serve as earth.
So might not be an earth(CPC) installed so would need to install one (re-wire) needed, you should only be using plastic or double insulated accessories on these circuits.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!