Well I turned glow worm combi boiler off , drained the CH , removed the
rad and capped ends OK

The lockout light now comes on after about 15s of turning the taps on -
the boiler seems to fire up and the 'demand' light comes on + I can
hear the pump starting .

Ive bled the rads and the refilled the system to 2.5.

I was wondering whether I have a pressure/airlock problem?

Many thanks