Its not clear from your post whether you are looking for support for yourself or someone else and I'm also wondering if by 'good value' do you mean affordable? A couple of resources that might be useful...
- Pre-pandemic they ran free support groups in Balham with creche facilities attached. I've had the privilege of training with the founder, Liz Wise, and even if these groups are no longer running she would be a good contact. Here is a link: https://www.cedarhousesupportgroup.com/about-2
- This charity have a free help line and a variety of support forums (text, email, private facebook groups) I used to moderate a one of their boards and know they are passionate about supporting mums from all walks of life. You can find them here. https://pandasfoundation.org.uk/
If you live or work in the borough you can self refer for free online or face to face therapy (be warned, face to face has a lengthy wait time) https://www.talkwandsworth.nhs.uk/
If you definitely want to go down the private therapy route, then you'll find therapists and counsellors affiliated with the appropriate professional bodies here, you can filter by price, location and speciality. I'm attaching a link to my own profile below as PND is something I've trained in and worked with,
https://www.counselling-directory.org.u ... -crickmore
However, I'd strongly recommend you speak to a few people and find someone you feel comfortable with - most will offer an complimentary call of around 20 minutes to ensure they are an appropriate fit for you. One thing to consider is if you are happy to work online with someone, look for a therapist outside of London as they are usually less expensive!
Best of luck with your journey and I hope these resources are useful.