Filling in air bricks

[George Hartshorn]

Hello,

My property has a concrete floor so the old air bricks are redundant, and the cavity behind them is quite large, resulting in condensation forming on the inside wall.

What should I use to fill the cavity, and what should I use to block up the hole once i've removed the airbrick?

 

[Alastairreid]

Glasswool in the cavity and same brick as existing to infill.
Is the new floor lower than the original ?