I highly recommend our architect, Kevin Clarke http://www.kjcarchitects.co.uk
We’re just finishing up our whole house renovation, loft extension and side return in Balham. He’s been great and very user friendly. Message me if you’d like any more info.
We've been using Decimus Design www.decimusdesign.co.uk
We've found them to be really good. Especially at dealing with the builders and sorting out problems on site. We've been really happy with them so far.
I highly reccomend studio werc. They are based in Tooting. They have done many of my friends and family’s houses and they have all said how fantastic they were with contact, professionalism and knowledge. http://www.studiowerc.com/