Is it normal when speaking for the lips to press/ put pressure on the gums and teeth when trying to articulate words?

It is normal. The articulation by definition is a word that refers to the way you position, press and move your lips and tongue against your teeth and the roof of your mouth to make various sounds that flow together as words. Hope it helps.
To a point. and the pressure is minimal. It depends on what sounds you are making. If you say "Ah ha !" I'm sure the pressure is minimal, in comparison to "fluffy" or fanciful". Try it yourself.