What a levels do you need to be a therapist?Watch
Would this be suitable?
Other than that, to best your chances at fulfilling your life goal, consider English Language or possibly something sciency. Philosophy would also be a viable option as it is less based around the curriculum taught within the subject itself, but is more subtly focused on developing your analytical and organisational skills, such as structuring essays or reports. English Language is also useful as throughout the A-level you learn about power, gender differences in language, the language acqusition of children, and other useful topics that universities are aware would enable you to become a successful student.
Sociology may also be a good option, and would potentially work well with Psychology and English Language (but more specifically Psychology). Many Psychologists or psychotherapists, or anybody holding or providing any kind of academic achievement in this field, tend to look down on Sociology as it is focused on more the analyzation of contextual reasons for specific things, rather than those within the mind or psychology of an individual.
English Literature and History are arguably, in my opinion, only really there for showing that you are capable of retaining knowledge and structuring it into an essay. They're more artsy-based subjects and wouldn't necessarily be important a career in therapy. Combine these with Psychology however and perhaps your choices would form into an effective foundation for pursuring your future contextual interests.
All in all I would seriously recommend focusing on maths if you want to pursue a career in Therapy. It helps a significant amount and many universities actually specify it as a condition of acceptance into Psychology.