Create a file with the following contents. Let's call it RCFILE (use the name you want).
source /etc/bash.bashrc source /home/USER/.bashrc source /path/to/env/bin/activate
(Replace USER with your username of course.)
Set up a profile with the following settings:
Command: /bin/bash –rcfile /path/to/RCFILE
In the profile manager, on the line of the profile, double-click the Shortcut column, and define a shortcut for that profile.
Now, when you use the shortcut, a new tab will be launched, the command will be run, and the shell will be correctly initialized.