There is no competition requirement for the jar to be sealed. With jam, yes, but chutney, no. The vinegar is sufficient to keep the chutney good for many years. The lid is only to stop it drying out, not to stop it going bad, as might be the case with jam. Best to use a plastic lid - metal will corrode quickly,and you may be marked down if you use metal without a sheet of polythene under the lid, if metal. Anyway, chutney should be potted up cold, so no seal normally forms. I have won chutney competitions at local Horticiltural shows, but nobody has ever expected the jar to form a seal. In fact, one winning entry was only potted up on the day. Do not use wax circles, or you will be marked down. The chutney should be at least a month old, preferably a year old, as it only develops its full flavour after quite some time. My latest chutney is now over 2 years old, and, if I say it myself, the flavour is magnificent.