Look at the lovely fudgy Weezolpaw!
Yay O re publishing. Don't give them all the rights - the days are long gone where you expect to get, er, paid for work, but you might in the future from someone else, so hang on to your stuff, you never know when it will come in handy.
They are making money out of you, basically, which is fine - up to a point. You want to sign off on 'one use from X to X date only in UK only'. They can pay you if they want to use them again.