I had Hayzy Dayz do mine.
They came to the house, left no mess, genuine part and was all fitted in about 45 minutes and took me on a test drive to demo the cruise control system.
£150, absolutely fantastic service, the owner and the fitter (Elliot) I had were very nice and I would thoroughly recommend them to anyone thinking to have cruise control fitted - no complaints or reservations whatsoever.
They're all ex VW mechanics and definitely know what they're doing. They also offer you a 2 year warranty on the parts and labour and will go to most places in the country.
the cruise control as a system is absolutely fantastic! That and fitting the arm rest have made my driving incredibly comfortable!
but yes, would thoroughly recommend Hayzy Dayz