As I said It's a leisure paced scenario, where you have time to plan and the enemy actions while very much not negligible, are also not overwhelming.
That's not a bad thing and as a matter of fact I liked it as a change from , for example, the recent mediterranean fury scenarios and their "survive four harrowing hours against an avalanche of more planes than you have missiles to shot at them with". But at the same time if you don't plan carefully the enemy will make you paid for it dearly, so definitely it's not too easy at all.
Also consider that I had the lucky draw with the HAWK SAM positionement. Another play can yield a substantially harder experience, so I wouldn't change the enemy forces at all.
If I were to change something it would be reducing a little the scoring for the armored units. Right now you can win with only two of the three stated targets, (the two armored groups and Marib AB) and that was with a far from perfect play, with plenty of casualities on my side.
If, for example, the "armor destroyed" poins went down to 20 for light armor and 25 for heavy from their current 30 and 35, the player would be forced to engage all three of the targets unless it made a flawless play without casualities.
So a slight reduction in the scoring for enemy armor it's the only change that I recommend on the enemy side.
On the British side, I gave a look with the editor and I saw that right now; the RAF radar in the coast has barely the range to detect anything in the border of the no-fly zone, so even if the proximity to the border triggers hostilities it's next to impossible for then to know where you are to come fighting.
I recommend either transform them in a "false alarm" menace deleting the Hunters to save CPU recourses (they weren't willing to fight after all, but intelligence didn't get the clues), or give them a longer ranged radar even if ahistorical (gameplay compromise) and a more reaching violation and prosecution zones (they were looking for an excuse to intervene didn't they?).
Finally here you have the Loses&Expenditures log, you'll see that while slow paced, there was action aplenty with both sides taking and dishing lots of punishment:
SIDE: Saudi Arabia
2x RB-26 Invader
8x Vampire FB. Mk52
6x M192 I-HAWK
2x Vehicle (AN/MPQ-33 HPI)
1x Vehicle (AN/MPQ-35 PAR)
1x Vehicle (AN/MPQ-51 ROR)
1x Radar (Generic 2D Air Search Radar [Short-Range])
16x Centurion Mk 3 Main Battle Tank
7x F-86F Sabre
25x Infantry Section [7.62mm MG/Unguided Infantry Anti Tank Weapon]
4x Venom FB.Mk1
8x 40mm/70 Single Bofors
18x 12.7mm/50 MG x 6 Burst [150 rnds]
64x 20mm Hispano Mk5 x 2 Burst [50 rnds]
12x RAF 500lb LDGP
2x 12.7mm/50 MG x 2 Burst [100 rnds]
22x 20mm/85 Vulcan Burst [100 rnds]
972x 40mm/70 Single Bofors Burst [4 rnds]
66x 12.7mm/50 M2 MG Burst
8x AIM-9B Sidewinder
1x Yak-9U Frank
10x Il-28 Beagle
2x An-12 Cub BP
2x MiG-15bis B Fagot
33x 20mm ShVAK Burst [20 rnds]
23x 12.7mm/50 MG x 2 Burst [100 rnds]
49x 37mm N-37 Burst [10 rnds]
49x 23mm NR-23 x 2 Burst [40 rnds]
319x 7.62mm MG Burst [20 rnds]
1934x Generic Unguided Anti Tank Weapon
29x 23mm NR-23 x 3 Burst [60 rnds]
8x 85mm M1939
144x 57mm S60 HE
12x S-5K 57mm Rocket
8x AA-2a Atoll [R-3S]
16x RS-82 (TRS-82) Rocket
12x FAB-500M-54 GPB
64x 23mm Twin Burst [20 rnds]
13x FAB-1000M-62 GPB
SIDE: Great Britain