Solution:

Up to a point

Solution:

Like there is no tomorrow.

Solution:

Three blind mice.

Explanation.
There are no i's in mice

Solution:

I understand

Solution:

Flat Tyre

Solution:

When we read the first brain bat upwards, we conclude the meaning to be 'Slow Down'.
In the second brain bat, when we read it downwards, we can conclude it to be 'Give Up'

Solution:

end up behind bars

Check that the word "END" is spelled in an upward direction behind three occurrences of the word "BAR".

Solution:

Give Up

SLOW when read down gives us Slow Down.
GIVE when read upwards gives us Give Up.

Solution:

Stand up comedy (stand up comma D)

Solution:

Mixing business with pleasure.(PbLuEsAiSnUeRsEs)