Are your blocks new? If so they are likely to be concrete or insulating blocks (technical point).
Answer to your question:
1. You can dot and dab. This is plasterboard bonded to the wall on gypsum dabs and skim finish. (make the walls sound hollow and is used a lot in new housing). Quicker to apply and less water, therefore less shinkage afterwards.
2. A two coat plaster finish. Something like Thistle Undercoat, bonding or renovation plaster as your base coat (correctly applied - not to a bone dry wall) and finish with a thistle multi finish.