According to Wikipedia, the UK prison population in 2014 is 81,905 men and 3,956 women (I have not checked the source of their statistics, but that sounds about right. The number of men in prison has increased massively over the last thirty years since I studied criminology, but the number of women in prison appears to be roughly the same order).
To answer the question whether too many wome go to jail, there are two issues:
1) Are women treated differently to men for the same offences and
2) Are custodial sentances in general used too frequently.
In terms of the first of these questions, one has to compare like for like crimes and those depend on the severity of the crimes.
To take an extreme example, if someone commits murder, there is a 95% chance that they will be caught, prosecuted, convicted and sentanced to the mandatory sentance of life in prison irrespective of their gender.
I have not studied the criminology research, but certainly there are more men in jail because they are much more likely to commit violent crimes and crimes against property. I believe most women are jailed because they are recidivists or repeat offenders of minor theft, fraud and drugs offences.
To find a comparitive offence, one must look at low value fraud or theft.
To decide whether woman are treated equally to men, the questions are:
1) Are they more or less likely to be caught and prosecuted: I do not know if the police are more likely to caution women or whether the CPS are less likely to prosecute women for a crime compared to men commiting an equivalent crime.
2) If they are prosecuted, are they more likely to be convicted (Alexandra suggests that they are and suggests that this is possibly because judges feel that women 'should know better' and because judges are mostly men) The judges I know are women, but they might actually be harder on women for similar reasons. However the proportion of women convicted could also be due to the CPS only prosecuting offences against women where they are certain of the result because the risk of a woman reoffending after only a caution is less.
3) If they are found guilty, are they more likely to be given a custodial sentance: again, I have not looked at the research which must have been done, but in sentancing judges take into account the stability of the offender's life, the amount of support a person have and the effect on their family life and on their family - particularly if they are a primary carer. Hence, most of the women who are sent to jail are not there because they have carried out violent crimes, but because they are repeat offenders (and often if they are guilty of minor thefts, this is usually because of drug problems).
Obviously, there is likely to be acasemic research on all of these questions and I would not like to take a view one way or another without looking at it.
The second question of whether too many people are sent to jail, I would argue that the answer is yes. All of the political parties in an effort to appear tough on crime have criminalised more behavour, put pressure on judges to give more severe sentances and brought in minimum sentances for some offences. The increase in the number of people in prison is a scandal. The number of people who are aging and kept in jail, have drug problems, have mental health problems and are former members of the armed forces not given adequate support all provide reasons for concern.
The issue of mental health problems and issues with drugs covers most of the women in prison; these would have much better out comes if given treatment and support rather than incarceration.
Finally the idea that people should be jailed for non-payment of licence fees is absurd. The licence fee is collected for a non-state body even though it's collection has statutory force. (I believe non-payment does not even count as a criminal offence.)
-----Eamon emailed the blog and got included. Because its a very relevant subject