Please evaluate my system...

Lose the Linn and get a Herron VTPH-2a.  Eventually get a better cart.

I not only have direct experience, I have owned a VTPH-1mc and upgraded to the VTPH-2 and then had that unit upgraded to a VTPH-2a.  I also own a VTSP-3a R03 preamp.  I am a Herron Audio fan because of their products' performance.  I have also owned Mark Levinson and Audio Research electronics, but ditched them for Herron electronics.  I have heard nothing better.  

A few OPINIONS on three of the suggested changes....  These are opinions based on my experience.  Others have probably had different experiences.  YMMV.

A nice and effective room treatment is just the addition of a lot of artificial plants.  Doesn't have to look like a tropical rainforest, just break up the reflected sound.  Will make a big difference and help reinforce the WAF.  

Vibration / isolation can be easy and inexpensive.  Vibrapod cones are very effective.  Maple butcher block works and looks nice.  A combination of Vibrapod cones and maple butcher block boards can make a difference.  

In my opinion, power conditioning won't make as much difference as an improved phono stage (1), room treatment (2) and vibration control (3).

Keith Herron is the best person to contact directly to determine the ease of getting his equipment into the UK.  It's not rocket surgery, but there is a process.