Treatment costs vary and will depend on location, type of therapy, as well as on the therapist’s current workload. I have seen charges that range widely, but therapists will generally only charge what is required to enable them to continue providing their services and pay their own bills.
The cost may be around £50 per session. Although this may, at first, sound expensive, when one considers that psychotherapy work takes a great deal of vigilance and personal energy, additional time on cases outside of the consulting room, fees to be certified members of professional bodies such as the National Counselling Society, expensive ongoing training (a requirement to continue as an accredited psychotherapist), and possibly the rental of a consulting room on top, the fee makes more sense. Additionally, your therapist will almost certainly have paid £5000+ and spent three or more years in training to reach a point where they are able to work with and assist you. But perhaps comparing what a garage mechanic will charge to fix your car, around £90 an hour, or a restaurant meal for two, around £60, puts life-improving psychotherapy fees more in perspective.
If you ever find yourself in a situation where you have a need for therapeutic help but are unable to meet the costs (your concerns may also be affecting your earning ability), ask the therapist if they can help you for what you can afford. Either they may assist people with your limited resources, or know of a therapist that does. Your GP and local council may also be able to put you in touch with someone who can help.
You may like to consider group therapy as this is often cheaper, or free, but it is still very effective. Group therapy offers advantages too, such as the support and understanding from others who are in a similar situation, and hearing what others are dealing with can also help one to know that we are not alone. On-line therapy is also an option, for example, via Skype (search Google for “online therapy uk” to see a list of organisations).
Your welfare is important, so ask for concessions when you really need them, and if the therapist you ask does not offer reduced rate sessions, ask them if they know a therapist that will. (See the links at the bottom of my welcome page to search for therapists in your area).