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. Many exams can be taken online.
Many unions run courses to help their members brush up the skills they need (e.g. reading, writing, maths, ICT and study skills) to progress on training and education courses. UNISON, for example, runs 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 often give you 'credit' for skills and knowledge you have demonstrated either through doing a job or piece of work, or on another learning programme.