If you want to sell your produce e.g. via a WI, Farmers Mkt or local fayre, I understand you should a) only use new lids b) try and use very standard jars - I think the WI members use only classic jam jars and c) you may be required to have your kitchen inspected by the local Env Health officers.

Also, I have been told that rather than put the date of making on the jar, it is best to put a use by date of circa 3 years from the date of making (though if you're using a low sugar recipe I guess it will need refrigeration).
And, of course, list all the ingredients.

I don't make jams and chutneys for sale so I just use standard jam pot wax circles and cellophane covers with rubber bands and for chutneys reuse jars and lids that have previously had chutney, ready made sauces, mayonnaise, for example. The jam pot covers are sold universally, my corner Spar shop sells them, so no need to go to Lakeland if there isn't one near you.

I've never had jam go mouldy or crusty and I've made jam off and on for 30 years.

Enjoy the fruits of your labours!