I have had Megan Spayed after speaking at length with my VET. The head nurse also advised that some sort of disease of the oesophagus can also be avoided if the bitch is spayed early. As to leaving spaying until after the first season, this may have been the advise given say two years ago but new medical information has superseded this advise in some vets opinions. The figure given for the decrease in risk of cancer and other diseases if spayed early outwayed problems such as possible incontinence and it certainly has not changed her personality, she was back bouncing all of the place within about 24 hours.
As to worrying about whether my spaniel was close to season and therefore a higher risk of problems in surgery due to increased blood flow in the organ, my mind was put at rest as this can be checked before surgery commences and if this is the case, then the surgery can be aborted.
Thanks to all those who posted advise as this really helped because I needed to know what questions to ask before feeling comfortable with my decision and having the vet proceed.