There are pros and cons with each of the choices you have. Gaining a certification (IF you pass 1st time) will require time to learn and revise the subject matter. From what you have said it seems like maybe you will have a bit of work to do on the Security side of things - 2-3 months by your guestimate). This is time during which you won`t be earning any kind of significant money; you may be able to fit your studies around flipping burgers at Mickey D`s but realistically you`ll want to focus your thinking on your studies to ensure you don`t have the added downtime of a retake. Also remember that having professional certs whilst undoubtedly beneficial, do not provide an instant "get rich quick". You`ll still have to start in a basic role and get a few years experience before any kind of significant salaries can be anticipated.
Taking an IT/Support role is a valid choice. You may not be earning a fortune but you will be gaining valuable experience and quite a few of the Security Certs require security-related experience. Depending on the work you do in the IT role you may be able to "massage" the roles etc to suit your requirements. Whatever else you`ll be pulling down some cash which whilst not what you may ultimately aspire to, will be considerably more than the f**k all you`ll get when taking the study path.
The days when pieces of paper meant everything seem to be increasingly a thing of the past and employers undoubtedly look favourably upon experience providing it is in an appropriate field.
Ultimately both choice have benefits and drawbacks and it depends on your own personal inclination. Most of all do what you want, what you feel would be best. Ponder long and hard before hand and consider all that is involved with the potential choices and then make your decision. But once you've made your decision stick with it, be disciplined and put the graft in and I`m sure your efforts will be rewarded.
Failing that sack it all, travel to the Amazon and drop a trip or two in the form of some native plantlife and see where that takes you. It`s all up to you mate ... try it and see!