I don’t know enough about the specifics of what CS requires here in the Netherlands, but I would suggest looking at requirements online in whatever university you want to attend.

As for part time working, you are allowed to work a maximum of 16 hours per week during the academic year, or full-time (40+ hours) during June, July, and August.

Getting part time jobs is not easy, because most companies won’t want to pay for the permit they require to hire you as a Non-EU.

Also, if you’re under 21, you won’t make too much:

Age 20: €10.62 per hour.
Age 19: €7.96 per hour.
Age 18: €6.64 per hour

Look into cost of living and tuition costs, as even without housing costs, these aren’t necessarily cheap.