Oh Fiona, i can't imagine how terrible that experience must have been, i was reading about another cocker that was rescued by the fire brigade and found my self thinking what i would do if Lucy went through the ice - my only conclusion was panic, short of carrying ladders or an inflatable boat around there is not much else you can do.
Tia is such a lucky monkey, i guess the lesson here is to avoid water wherever possible in this weather. give them both a good squidge from us and calm down with a mug of hot chocolate