Share 'Loft conversion recommendations and advice...'

Hello everyone,   Due to a rapidly expanding family we need to convert the loft of our Bounds Green terraced house into a bedroom.   Has anyone had a loft conversion done recently? Which builder did you use and can you recommend them (or warn against them....)? Any other helpful advice about the pleasures and pitfalls of this type of project would be much appreciated.   Many thanks Toby