I do CBT, and other stuff. 20quid sounds very cheap, which would slightly worry me. CBT practitioners should either be chartered clinical psychologists (you can check with the British Psychological Society) or therapists registered with the BABCP (British Association of Behavioural and Cognitive Psychotherapies). Be very wary of people without accreditation - anyone can call themselves a therapist, and anyone can say they do CBT. And people can do an awful lot of harm if you let them into your personal life and secret feelings. So be careful. Bad news is that clinical psychologists and CBT therapists are expensive (I'd say anywhere between 60-100 likely - 30 is a counsellor, so may only have a very basic diploma in CBT, but may be good). Some therapists have discounted rates for people on low incomes?
On a positive note - CBT for anxiety has quite a good success rate compared to other things like counselling. PND in my experience is very complicated and varies - some women have a pure type of depression, very low, others have anxiety and fears and panic attacks. I would treat these things differently, so you need to be sure you get a decent assessment.
Can you try your GP for referral? Adult MH services are often crap, (long waiting list) but sometimes there are better services for women through maternity services (try HV or Sure Starts?). Also, if you or your partner have access to private health insurance (via work??) you could get private therapy (which would be an accredited person) through that more quickly.
In NHS you can get prioritised if you are feeling very very low and at risk of harming yourself. This may not be you at all, but just so you know that if it is that urgent you can push. Some GPs can be supportive if you highlight how urgent it is in terms of you being a parent and you not wanting things to affect your child. I think the important thing is to be pushy and not to get too worried if people get annoyed with you - pushiness tends to get people services.
Also there are voluntary agencies around in many areas that provide counselling (but again be careful of quality). And CBT self-help can be quite good (Mind over Mood - CBT book).
I'm really sorry you're feeling so low, and wish you loads of good luck in finding some help.
Take carexx