tapping noise from top of vauxhall engine?

ive got a astra 1.6 and got a tapping noise at top. ive done a engine flush and oil change a few weeks ago now got tapping noise. I check engine level its ok. does noise appear due to lack of oil pressure due to only doing short journeys or does doing short journeys not cause the noise. I understand u need oil pressure to circulate oil to oil cam but I don't know how to get rid of noise.