Running

I don't think you need the 12 miler certainly, and agree the hills is too soon after your HM

having just done 2 HMs with a 3wk gap, mine looked like this. I have a half iron in a few weeks so most of my 'Rest/CT included a turbo/swim/gym, but I don't imagine you'd need that volume)

Sunday: Big Half

Monday: Rest / CT
Tuesday: easy track, ~12x200m, 200m recovery between (200s were stretching legs rather than 'fast')
Weds: Rest / CT
Thurs: 3 x 2k 'tempo' (around HM pace). (2k warm up, 2k warm down)
Fri: Rest / CT
Sat: 14k easy run
Sun: Rest / CT

Monday: Rest / CT
Tuesday: 5x1200m track (+ jog there + back)
Weds: Rest / CT
Thurs: 40mins 'tempo' run (bit slower than HM pace) (+warm up, cool down)
Fri: Rest / CT
Sat: 90min tempo bike, 10k brick run
Sun: 13k run to gym. HIIT intervals thing. This was silly. I was already knackered having done legs at gym on Friday, and turbo/brick on Sat - it was just that I'd agreed to do the session beforehand. Ho hum.

Monday: rest
Tuesday: 30min easy spin turbo, track (3 x 800, 600, 400, with 200 recovery between)
Weds: Rest / CT
Thurs: 30min easy spin turbo. Run 12x200m leg stretcher, 200m recovery
Fri: Rest / CT
Sat: 3k v easy run with a few strides (short 100m increasing pace)

Sunday: Outlaw X Run Leg

Essentially, a few easy speed sessions to get your legs turning over without getting too tired.
And a few 'tempo' sessions where you're getting used to target race pace without doing so much you wont recover. And make sure you have a bit of a taper before the race, as you wont really gain any significant fitness in 3 weeks so it'll be mostly about being fresh on the day.