I've had my hair keratined one before but decided to give the London Academy a go. You have to sign up to receiving texts which offer cheap or free haircuts/keratin. I got one day before yesterday offering a keratin treatment for £30. Texted back and had an appointment today.
It was a really good experience. Everyone was friendly and my student hairdresser was just doing a refresher course. She took her time and applied it in small sections before carefully blowdrying. I never got the impression that I was getting a substandard service. In fact this hairdresser took more time and effort than my previous experience (where she only used the hair straighteners)
One recommendation - if you go - bring a sandwich as if you're having colours or keratin you'll be there for about three hours. But I'm really pleased and for £30 - it's amazing if you want to treat yourself.