If you are thinking of applying for a teacher training course, you will need to take the numeracy and literacy skills tests as part of the application process, and ensure you have passed them both before the start of the course.
The first attempt at taking your skills tests in each subject is provided free of charge. You can book up to two resits if required, but you will be expected to pay for these yourself.
You can book your tests in advance for a date by which you are expecting to have submitted an application. When you take the tests you will need to provide proof that you have applied for a teacher training course. The tests are held at a Pearson Professional Test Centre (which also delivers Driving Theory tests, so you may be familiar with them already).
You can also view practice material to help prepare for your tests.