Any jam experts out there?

I made marmalade using the mandarine windfalls that were so sour.... first lot set ok so made some more, ended like water in the jars so re boiled it the next day and it went like cement! third lot took ages to reach setting point (got a sugar thermometer now)
Now John.... Lemon curd........... my lemon tree has hundreds of lemons on, fancy a trip over to lemon pick when they are ripe?