That's an expensive route to go down.
I've just had a quick look around an maybe Amazon Japan might be a good option. You'll have to create a new account, even if you have a UK Amazon account already.
But you won't see much change from £400.
Maybe used on eBay is another option but completed listings are still around the £300 mark.
Maybe look at getting a £30-40 upscaler to start with and see how committed to retro you still are after a while before investing £300 or more.
Personally I'd try and find room for a CRT TV, even if it's just a 14" portable and spend the money you've saved on games.
This came yesterday. Another import PS1 game in a standard CD case.
This one came out in PAL regions but I only paid £13 delivered for it from Amazon Marketplace of all places, so cheaper than the PAL version by about 50%. I've got a few more on order from there as well that are way below eBay prices.