Re: The main question is...
The touted MSP for the 4080 has reportedly been as low as £700, although getting cards at the MSP is likely to be next to impossible. You'll probably end up paying something like £1250 for a 4080 when it lands, if you are desperate to buy one in the first 6 months. You can get 3080s now for £850, which is about £500 less than 2 months ago.
So I think £1,000 for the 4080, rather than £2,000 for the 3090Ti isn't too far off the mark. You might even get it for less if you can find a "founders edition" one on launch day, although I wouldn't hold your breath.