I have never flown a Javelin (or any jet, delta or not) but have part-owned a Chipmunk for well over 30 years. I can say the Chipmunk spin is nothing like the description of the Javelin spin. It is recovered in the usual manner - power off with ailerons central, full opposite rudder, pause, stick forward until the spin stops (might need a lot of forward stick!), then centralise and ease out of the dive. I have never experienced a Chippy flat spin (if it can be made to do it...).
I also flew the Yak 52 for a few years and did flat spin recovery in that as a flat spin can be inadvertantly entered of a botched aeros manouvre in the Yak. That spin is stable and flat with a high rate of rotation and descent. There is no pitch occillation, and it is recovered with power off, full oposite aileron with full down elevator (so stick hard into the front corner), and full in-spin rudder all simultaniously, controls centralised when spin stops. Agaian, this is nothing like the Javelin spin description.
The Javelin is an odd configuration, being a thick-winged delta with a tailplane. Deltas don't usually stall in the conventional sense, they just reach very high drag rates at high AoA wih associated high rates of descent. But, as was observed in the Concorde crash at Paris, they can eventually 'depart' in roll, though Concorde of course had a narrow and thin delta wing with no tailplane.