Short-notice (september) celebrant required in Cotswolds area

Hi,
My fiance, toddler and I will be coming over from Australia in August/September and were desperately hoping to organise a small commitment ceremony to be witnessed by our UK family and friends. We have a venue available to us near Bourton on the Water for September 7 and, for a number of reasons, would be requiring something very personalised, relaxed and low-key. Is there anyone out there that might be able to help us? Thank you so much!