Is Warcaster necessary for my multiclass?

I’m trying to play a redemption paladin with 2-3 levels of celestial warlock. The warlock is mainly for cantrips, additional healing and backstory 

I was gonna play a variant human and take warcaster so I can spell cast with my sword and shield, but if i understand action economy, I could put my sword away as a free action, eldritch blast the flying enemies and pull my sword back out the next turn to attack if needed. 
if that’s right, do i need warcaster?

And if i dont, then do you have any suggestions for other feats i should take instead? Or maybe even a different race to play to get more benefits than a human?