28lb was a training round in its own right.
1000lb bomb came is HE, HES or Inert. The latter was blue and was a 'shape' with an operational tail. HE(S) was a rare and perhaps mythical beast, I never saw one but it was in the stats. The requirement to drop two single 1000lb HES in each training period.
Up to 1966 the nuke was YS2. A number may have been dropped inert at West Freugh - I was at Waddo when a lot were dropped to prove the 2H attack profile.
I believe HE(S) was with only a small charge of 50lb HE also known as HE (Sand) or (Substitute) but that is rumour in confidence as I never saw one from 1964.
HE was either Mk 11 or Mk 12 (at that time) identical profile except one was of cast iron for airburst and frag and the other was forged for penetration and cratering. On 35 we certainly dropped a fair number in Cyprus either single or in sticks of up to 14. The earlier picture of Baz Gowling dropping 21x1000 117 tails was for a fire power demo. Our drops were usually pop up to 2,500 ft with 107 tails basically to get rid of stores approaching life expiry. That was 1971-73.