you have everything you need. There are more channels than you can shake a stick at.
If you want a Freesat box the Humax FOXSAT-HDR is the one to go for. It's expensive, but very good.
You'll need two feeds from your dish if you want to record on the Humax as well as watch a different channel, and added to the two feeds to the SKY box that means you'll need a quad LNB. if you only have a dual you'll not be able to operate both boxes.
click here and you'll see a list of the available Freesat channels