goldfish over winter

Hi

I moved into this house a few months ago and inherited a pond with about 20
goldfish in it. the pond is about 12" deep 20' long and 6' wide, it is
quarter filled with lilies and other plants.
I do not have a clue of how to look after them properly, they are lovely to
look at and I would be hurt if anything happened to them. I read that I
should stop feeding them from November to April, is that correct? I am so
busy dealing with urgent repairs that I have not got round to the fish yet,
the place is so overgrown that I cannot even find the pump. Apart from
finding more time, what is the best thing I can start with? I live in the
south of England and we have very mild winters generally.

Regards

Charlie