Can somebody tell me if i can use the Copland CTA402 integrated as a preamp to match it up with the monoblocks?
No, you can't.
First, it appears to not have preamp output jacks. It just has tape output (and input) jacks, which presumably are not controlled by the volume control.
Second, most or all tube integrateds (or more precisely, integrated amplifiers that have tube power stages and output transformers) should not be used as preamps, because operating the power amplifier section without a speaker load can cause damage.