There are inevitably a couple of facts and a couple of shades of grey.
You don't need Lightning II or Typhoon. You might want both or either..but you don't need them.
However, you do need a Lightning II if you want to keep pace, for a little while, with threat SAM systems. You need Lightning II because the only alternative is F-22 or not going. You have never needed Typhoon. Typhoon has been desirable but in no way essential. There were and are plenty of COTS aircraft that could do the QRA role and everything Typhoon has achieved overseas.
So, it's just a case of where you set the bar really.
Freedom of Action at a high tariff? Gen 5.
CAS and strike unopposed...anything you like from Buccaneer onwards.
CAS and strike with a medium air threat...same again, just take some HARM/ ALARM shooters with you and a Growler or two.
Guard the UK against Russian snoopers and rogue air liners? F-3 or equivalent.
The cure for all ills up to the 95th percentile? F-15E or F-18E.
Want to keep shovelling money down a black hole trying to get an AD platform to work as well as an F-15E or F-18E in the air-to-mud world but failing. Typhoon's your answer.
Whilst we wait for the ferociously expensive Lightning II we are actually not doing ourselves any favours on the messaging front by continually turning a blind eye to the costs of Typhoon upgrade, costs of Typhoon support, the aircraft's short comings both air-to-air and (stifles laugh) air-to-mud...and the fact that we didn't actually need it in the first place. But then again we do (genuinely) need chaps with top buttons undone...so maybe it's money well spent.
As for the boat? Naval aviation is very simple: Do it well or not at all. At the moment it doesn't to me look like we're doing it well. Maybe the next generation can pull the rabbit out of the hat...although I suspect we've armed them with a hat full of dog mess to do it from.