No idea about Family Affairs but Live from Studio 5 regularly gets 0.2m... the lowest for any peak time programme on a terrestrial channel... and lower than most programmes on CBBC on BBC1.
Does LFSF count as part of Five's news output and as part of the Sky News supply contract? If so then you can't really compare its cost with that of Monkey Life, as LFSF will be part of a larger deal (and not have an individual cost in the same way as a standalone commissioned show) and will also have a value to Five in hitting their PSB quotas...