Anywhere south of London ( leaving Cornwall out because it likes it that way) and you can get to France, Spain and Jersey I in less time than it takes to get to Blackpool. And obviously the glittering capital is a painless train/ drive away. And Gatwick and Heathrow are easy peasy ( plus additional local airports)
Once again: there are airports other than Heathrow and Gatwick. Blackpool is quite easy to get to from up North, even if it is a long trip from London. City and suburban northerners can catch flights to the continent as easily as Londoners, from smaller, less crowded airports.
Not sure that I would consider Jersey a goal, but I will admit, I can likely only get there by going to London first. Though, if I wanted an island holiday where they speak English, there are others, up north. You will never, ever, convince me the south of the UK/Jersey is warmer enough to matter. I am a native of Florida, who lived a long while in Southern California. brits may disagree, but IMO, it is never hot anywhere at all in the UK in the summer. NO, really, it isn't. In winter, and except for mountainous areas, snowy and mild, or snowy and cold can strike anywhere. Places down south had a worse winter last year than Glasgow did, for example. The warmer down south argument isn't reliably true in winter, bor enough to matter in summer. And it will probably rain anyway.
I lived in Essex before, and getting anywhere by train usually involved going to London first, which was ridiculous when the goal was somewhere up north. Trying to go west or south by car involved going AROUND London. Ugh! Both situations involved half a day. I never had the luck to be able to fly out of Gatwick. Getting to Heathrow was a right pain, either an hour into Liverpool St then across to I have forgotten where and another hour out. Alternatively, over an hour by taxi. In either case, we had to take rush hour(s) into account when purchasing the ticket as that could easily change the trip from 2+ to 4+ hours. Most of us up north accessing other airports can get to them just as easily as Londoners get to Heathrow or Gatwick, and more easily than southerners not actually in London can and easier than some Londoners on the edges. Even if we still have to connect via a London airport to our final destination, getting a flight from our local is no harder than getting across or around London.