Don't worry if you haven't done any learning or training for a while: most people on any course you sign up for will be in the same boat.
And set aside any bad memories you might have from when you yourself were at school: adult learning is all about helping you overcome any obstacles you come across.
Most importantly, don't get hung up on exams: working through the course is what's really important, and lots of qualifications are all about assessment, and anyway, many exams these days can be taken online, not with pen and paper in a draughty hall.
Many unions run courses to help their members brush up the skills they need (eg, reading, writing, maths, ICT and study skills) to progress on training and education courses. UNISON, for example, runs the Learning and Organising Services (LAOS) which promotes lifelong learning both nationally and at local level to its members.
Your previous learning and experience can help you gain
qualifications. Course providers and assessors can give
you 'credit' for skills and knowledge you have
demonstrated either through doing a job or piece of work, or on
another learning programme.
To help you choose the courses that might be useful to you,
skills4schools has developed a unique 'journey planner'
which you can use to help you identify the next steps to take
on your learning journey.
There are very few courses relevant to school staff which
have rigorous entry requirements (eg, GCSE passes in particular
subjects at particular levels).