There are few misapprehensions in your original post, and it may be useful for you to be aware of the following.
If you want to be a therapist there are several ways to do that. Clinical Psychologists are one kind of therapist, but there are therapists from other backgrounds. Some train in healthcare fields like nursing, counselling or occupational therapy, whilst others train independently without a clinical background. In fact you don't even have to go to university at all to be a psychotherapist or counsellor.
While clinical psychologists do therapy, its not all they do. For example, In my day to day work, I spend about 40% of my time doing therapy, 40% doing supervision and teaching, and about 20% doing research. Others may do things like cognitive assessments or various other non therapy tasks. I would say if you want to be a therapist, being a CP is probably not the best way to go about doing it. Also we don't all work in hospitals.
To be a clinical psychologist you do not do a PhD, you do something called a DClinPsy which is very different. You can read all about this on
www.clinpsy.org.uk. You are right that the average age of clinical trainees is in the mid to late 20s and will have to go through extra study or lower level posts in order to be a viable candidate. Also not all CPs will be earning £60,000 salaries. Ones that are consultant in management and leadership roles in the NHS or specialist roles may, but the sort that spend their bulk of time delivering therapy certainly won't be.
Also be advised UK clinical training is not accepted in the US. To work in the US you would have to re-train to some extent and demonstrate you meet US licensure requirements.
As for your question about what to do, I think
1) You need to research the field more thoroughly and get an idea of what clinical psychology, psychotherapy, and couples counselling are and what is required. You can get this from your university and asking professionals in those fields.
2) If your heart is really not in it, thats probably not a good sign. Any field where you are going to be dealing with vulnerable people or those in distress requires a high level of commitment and dedication. Its not really something you can do lightly, and to be honest for the amount of work you do, you could be better paid, doing other work (and more quickly and easily too).