Well before you get into inserting things in the CI slot, you can only get signals from the satellite or satellites you can align a dish to.
So a fixed dish with a single LNB (presumably aligned to Astra2/Eurobird at 28E) will only get that cluster.
If you want other Satellites, you need either another dish aligned elsewhere, a multi-LNB bracket for your existing dish (along with a DiSEqC switch) or a dish fitted with a motor.
BTW: The Humax is a Freesat receiver, not Freeview: The latter is Digital Terrestrial via a conventional aerial.