In the past, it was a requirement that you had to train and work as a teacher before you could begin training as an Educational Psychologist. You don’t have to do this now, but you will still need to gain lots of relevant work experience with children (the 3-25 age range), in an educational setting. There are a very limited number of training places available each year so competition is intense. Volunteering is good (particularly to gain experience with the wide range of ages (3-25)), but you will also need evidence of substantial, relevant paid employment (currently equivalent to 12 months full time work). Teaching is obviously one way to get this experience (and probably the best option – see comments below), but you could also find it through spending time in an educational environment in other ways, for example as a classroom assistant, learning support assistant or mentor.
To get into these types of jobs you will need to demonstrate experience of working with children during your degree and both classroom and non-classroom based experience is relevant. For educational psychology it is really helpful if you can gain work experience with children who have special educational needs (physical disabilities, learning disabilities, emotional/behavioural problems).
The Educational Psychology section of this webpage gives you an overview of what kind of work experience is relevant and which organisations might support it:
You might also find the following job sector pages useful: