Post PPL, your options depend on your financial strength and flying regime.
Assuming you're a good weather pilot, you could advance your flying skills by transitioning to a more complex aircraft with advanced avionics. Mastering the flight envelope of a complex aircraft and its instrumentation will elevate your capabilities of navigation any airspace with greater confidence.
If your intentions are directed towards flying in the clouds and bad weather, an instrument rating is the right cetification to attain.
You're the pilot in command, so you have to determined the best route forward.
WP