If you go with speakers, my advice would be to try and get a pair of Magnepan MMGs. Frankly, I haven't heard anything that can touch them, even at 3x the price (that isn't just a theoretical 3x -- after much research, I bought what I considered to be the best speakers available at 3x the price. Then I heard a pair of MG12s -- nearly identical to the MMGs -- and promptly put the more expensive speakers into "storage" until I could sell them -- the Magnepans were CLEARLY superior). There has been a flood of positive reviews of the MMGs recently, just look around.
You do need an amp that is stable into a 4 Ohm load, and they require a fair amount of power, but fortunately, several Emotiva amps pair quite nicely and don't cost a fortune. Something like the Emotiva XPA-200 would do nicely.
The one fly in the ointment is that I don't know how expensive it would be to have a pair of MMGs and an XPA-200 shipped to the UK. Nor do I know if there are European dealers. But in any case, this is a great pairing.
But contrary to the advice above, I would recommend going for a pair of headphones, the HD800s to be specific. There are things speakers can do, that headphones cannot, but there are also things headphones can do, that speakers cannot. Putting issues of resolution (where headphones excel) and bass impact (where speakers excel) aside, I simply find that headphones give me much, much greater flexibility. I can listen to my music whenever I want, at whatever volume I want, without disturbing anyone. And while I love my speaker system, I love my headphones more.
Take a look at my Head-Fi profile here:
https://www.head-fi.org/u/163295/amcananey -- To put it mildly, I have heard a LOT of headphones and a LOT of amps. I have been STUNNED by the combo of the HD800s and the Crack + Speedball. I actually disagree slightly with Jim, as I don't find the HD800s to be fussy about amps, but they clearly do better with OTL tube amps than with solid state or WOT tube amps. And out of all of the amps that I have tried (including the Woo Audio WA22, a fully-balanced Beta 22, a HiFiMAN EF-6, an ECP Audio DSHA-1, a Violectric V181 and an AMB M^3, among many, many others), I have found the Crack + Speedball is EASILY the best amp I have heard with the HD800s, in a way that simply takes my breath away. You will not be disappointed with that combo and it will trounce whatever speaker setup you can put together.
Best regards,
Adam