Willow Given the chance what sort of employment do you want to do?,, do you want to be a hairdresser for instance, or a teacher. I ask this because you may be better forgeting GCSE and taking qualifications in your prefered career.
At 18 you are old enough to sign a tenancy agreement for your own bedsit or flat, but before you start looking you need to be able to pay for this, your local council can in some circumstances pay your rent in the form of a rebate.
So go to your local council, ask to see someone, privately if possible, explain about your home conditions and ask them what is available to you, there may be some emergency accommodation that you could use temporaly until you can see a way forward. There may be a charitable organisation like the YWCA who have bedsit accommodation for young people in your area.
If the council can not help you go the the Citizens Advice Bureau and ask them, This would allow you and your mother to calm down and hopefully rebuild your relationship.
If you are estranged [apart] from your parents you may be entitled to money from the state to pay for essentials, this may also let you do some courses for free.
Judging by your posts on here you are intelligent and just need a nudge in the right direction, don't worry about not being able to use the washer etc, help is always available if you know where to look, and this site is as good as anywhere.
What job do you want to do?