You should definately have holes in the top of the cloches for the plants to be able to get air through, this also helps with the condensation problem. You do want to keep a bit of condensation though as it will eventually run down the sides and help keep the soil moist. I also helps to keep a bit of humidity in the the cloche (winter air is usually very dry).

For the bigger plants in pots, you can also try building a small “tomato frame” out of thin bamboo poles and wire and then wrapping it with plastic sheeting.