Have a look at The Supplier, got a good review in Hi Fi World. I can't vouch for it myself, but the interconnect I've bought from there, encourages me to return - good value and great quality.
It's also cheaper than Russ Andrews.
Have a look, or ring them up and have a chat. Very friendly.
Maplins sell a 6-way block which is also a mains conditioner. Has been very well-reviewed in magazines and on other forums. Code is L07BK. About £40 http://www.maplin.co.uk/Search.aspx?criteria=tacima&doy=6m9&source=15
I purchased a Tacima CS929/BP 6 gang mains conditioner from Hi-Fi Care on Tottenham Court Road and it has tightened up the bass response from my Rotel RCA-855 and RA-820A set up. I thought it was a noticeable improvement though I'm sure the level of refinement is related to the quality of your mains supply.