kcockayne - I had a similiar thought in 2014. Booking as a normal scheduled flight in advance without a week's accommodation was largely impossible.
The only thing that the charter travel agency would consider was selling off seats one day before flight date on flights from mainland UK, or up to a week in advance for flights originating in Jersey. This was on the basis that holiday bookings from mainland UK less than a day in advance were unlikely (or, at best, should be considered distressed stock) and better to get some revenue than none.
If you want to take up this option, you'll have to phone Jersey Travel and ask nicely.