Generally speaking, if you require a staff member to attend a training course or participate in learning and development activities, you should pay your employees for their time. Where the training can be seen as a learning opportunity open to employees to attend if they wish, and therefore voluntary (e.g. a product information night to enhance ability to sell a product your business stocks) then this does not usually have to be paid. Similarly, where employees wish to complete training, or other self-initiated learning and development activities, it is at the discretion of the employer as to whether or not study leave or other assistance is provided. Any financial or time allowances/assistance provided will of course have likely flow on benefits to the organisation in terms of morale and retention rates.
However a business wishes to approach these issues, details should be included in a relevant policy (e.g. Leave Policy including Study Leave) to avoid ambiguity.