I have an ideal w2000. It leaks water when c/heating runs?

I have a w2000 boiler about 20 years old. It leaks water when the central heating runs. Is this some kind of gasket that might need replacing ?
Also when the c/heating finishes its cycle a tremendous rumbling and gurgling noise comes from the loft space. Any hints help or advise, anybody.

Thanks Andy.

Andy
December 2010