Buy a basic set of tools i.e. Trowel, handboard, bucket trowel buckets and summer to mix with. if someone says yes having your own tools will help. You need to start volunteering your services to family and friends (word of mouth and experience) but stick to what you know you can do.
you will get the odd plasterer or builder who will give you a shot but your wage expectations and what you will be worth to them will probably differ wildly, ( you have got to play the long game)
If you have family or mates or even mates of mates in the building game pester them for contacts\opportunities.
Remember who you know will generally get you further than what you know.
You have explained your personal circumstances but, if it is what you really want to do make it work i.e. Take a part time job keep up college and do govie jobs of a weekend. Some of them may have to be foc for family but it all gets you nearer the finish line.
good luck with it but if you don't get on with it divint fret, even if you have to take a job which as you said is a dead end, remember, nothing is permanent keep looking and keep trying.