First-off, I'd personally agree about the need for nukes, but would suggest that without the need to penetrate Moscow's (largely mythical) ABM defences, Trident is unnecessary. What was needed was a stand-off replacement for WE177, which would have been cheaper and more versatile.
Jag idea is undeniably 'second-best' in payload/range, but it's achievable cheap capability, and the Cosford airframes have about 4,500 flying hours left 'on the clock' each, without requiring an expensive MLFP. (And a more cost effective way of deploying low-level - in both senses airpower). In an ideal world we'd just go and buy 60 F-15Es to cover the capability gap, but it ain't going to happen. And the beauty of Jag is that its now accepted that we don't need to involve BWoS in upgrading it, an existing infrastructure is in place, and each new one requires only one new aircrew chap or chappess. With regard to single-seat night designation and the Harrier, I'd venture to suggest that the Harrier's problems were more the result of attitude ("Using TIALD is just like using ARBS, we don't need to practise it that much") and a poor TIALD integration with latency problems. I draw my noble friend's attention to the success Jag had with night designation in Bosnia in 1995, achieving a 'high 90's' percentile accuracy still not rivalled by Tornado/TIALD or Harrier/TIALD.
FACT: The GR4 as it is now (without Raptor, smart weapons, the required mid-life fatigue programme, the new main computer, etc.) comes in at £6.7m per jet. The existing Jag upgrade works out at around £1m - with a better AMLCD, ETAPS and EFRCs, a Helmet Sight, wiring for digi-ASRAAM, TIALD that really works, a better nav solution, better weapons aiming (can't spell Runge Kuttar, can anyone please help), and (very soon) EO GP(1) recce pod. And it's cheap to keep and cheap to operate, with total hourly operating costs (including DLO and HQ overheads) estimated at one tenth those of the Harrier, and one fifth those of a Tornado.
In essence, you could have two extra Jag squadrons for about £20 m (£400,000 each - the non-recurring costs have already been paid, plus a Major for each aircraft). This kind of money would get you three GR4 upgrades, always assuming that you had the spare Tornado airframes to upgrade, and ignoring the fact that they'd soon need structural work.
My sources suggest that a UOR for ELS on F.Mk 3 was actually issued during the Kosovo thing, and was then cancelled when the war stopped. With regard to technical difficulty/cost it would be easy and cheap for DERA/DARO, and probably very costly if given to the 'w@nkers from W@rton'.