Lambda calculus is simple and easy to understand. I learnt it in university from scratch and I think that everybody can do it. Set theory has a quite similar, manageable, learning curve.
And set theory and lambda calculus have nice 'interoperability' (e.g. λx[Dog(x)] is a characteristic lambda function for the set {x | x is a dog}.)
Yes this sound unrealistic in most cases. Taking a leave from your current job to try out another one is very risky.