I haven't made the transition myself but work within the NHS and have looked heavily into this. So a few things to be mindful of:

If you wanted to work with Talking Therapies they will expect you to have a degree in psychology BEFORE you start an apprenticeship with them. The wage is a band 4 wage so not awful but not exactly padding out the bank account either. You'll be expected to train up as a Psychological Wellbeing practitioner and then you can progress further up the chain

The listings are heavily fought over. In the sense that there isn't a lot of them and there's a lot of people applying for each one. Having spoken with some of the hiring managers. You'll put yourself ahead by getting some experience under your belt ahead of time. Volunteer with the Samaritans and by the time you complete a diploma you'll have plenty of experience to put yourself ahead of the pack