I am hopeful that I will attain Anatta. After I attain Anatta I will cease to be expressible. That hope motivates me to give up the clinging to forms, feeling , perception , consciousness etc... But what about the clinging to the hope of getting Nirvana...? Should I give up hope of getting Nirvana in order to achieve Anatta or Nirvana ?
Nobody attains Anatta. Everything is Anatta to begin with. It's just an aspect of all realities. I think you have Anatta confused with Nibbana.
Desire to be free from desire is desire again. Make right effort i.e. meditate without desires...and strive towards final goal with desire to attain nirvana but dont start craving...in the end tine will come when the final desire will drop itself.
Your question reminds me of this sutta, when Buddha told monks it is normal for oldest prince born from a great king and rightful queen. He is from righteous blood line 7 generations up, endowed with physical strength and intelligence. It is only normal for him to expect to inherit the throne when time comes. So do monks who has 7 factors for enlightenment. It isn't unusual for them to expect nirvana. I don't believe Buddha said anything about how to deal with the "hope/expectation", as long as you have 7 factors of enlightenment
again, i maybe someone with better memories than me could help me recall referencing sutta number. thanks.