Yes, so agree with Hedgehog.
Senokot is for relieving constipation, not for preventing it. You need something more gentle to prevent it happening in the first place eh Psyllium Husk, fibresure.
Senkot isn't for regular use. It's a stimulant laxative and could reduce the sensations of the intestine, which can end up with you being laxative dependant and having to take it all the time.
Much better to take a preventative.