Hello
The simple answer to this question is no, you do not require GCSE's to get a job, however it is preferable by many employers that you have some GCSE's in core subjects such as Maths and English and these could be either C or D's depending on the job you are applying for.
Many jobs which are well paid will require you to have good GCSE'S, A levels and a Degree, you would be shutting doors if you did not even attempt to do some GCSE's.
There are many people who do not have GCSE's and still managed to get a job doing what they love, but it does take a little longer due to competition being fierce amongst your age for employment. It would be more beneficial if you were to obtain at least the important GCSE's to enable you to get your foot in the door so to speak. There are apprenticeships which are available but a few do require you to have at least a D in Maths and English to do them.
You would be able to go to College and study your GCSE's rather than school if you wanted to, your best bet however would be to continue to go to school and do the best you can so that if you did badly then you can learn from your mistakes and if you did well you wouldn't be looking back with regrets saying "I wish I done them at school" You only have one life so you might as well try the best you can in order to be able to give you the best start in life
You could also look at going into retail, there are many jobs in retail where GCSE's are not a requirement but more experience and people skills, however you may find it hard to progress into a higher job without having GCSE's due to their requirements
Overall I would suggest the following
1) Continue to go to school to try to get at least some GCSE's so you remove the inevitable 'what if' in the future if all goes pear shaped if you didnt go to school.
2) If you do not do so well at School doing your GCSE's then redo them at college.
3) Get a job in retail and try your best to progress (gain some qualifications later on)
4) Go self employed and become an Entrepreneur
All the best