British Pregnancy Advisory Service (BPAS), says that “for women who are not in a relationship, the morning-after pill is even safer than the contraceptive pill because it is only an occasional dose of hormones, although obviously it doesn’t protect against STIs”. The BPAS states that “there is no limit” to how many times you can use it.
Because time is crucial to the effectiveness of the morning-after pill the Family Planning Association (FPA) believes that women should be encouraged to keep emergency contraception in the same way that people keep a supply of paracetamol or antihistamines.
Considering people 'not in relationships' are probably in a higher risk category and those who should be using condoms to prevent STDs, I'm not sure having a stock of morning after pills would help with the responsible decision making in the heat of the moment.
Although the handful of times I have relied on the morning after pill there has been at least a 36 hour delay (from Saturday night to Monday morning) to being able to get access to one, this was though in the days before they were able to purchase over the counter rather than by prescription only.
In the words of a good Girl Guide - be prepared.