Hi Sandman, did you see my reply in your other thread? I'm really not convinced that you need to do any serious chasing with that set up, especially as you can run the speaker cable up the wall behind the cabinets.
Also, if you want to be really neat you could always simply cut or chisel a groove into the plaster deep enough to bury your speaker cable then plaster directly over it, given the relatively short distance you need to cover.
So, the easiest way is not to do it at all! But if you're determined then look for the shortest possible stretches of wall and keep it cheap and cheerful. If you're careful you could do the whole thing with a stanley knife and a tub of no sanding polyfiller... good luck, whatever you do...
(Also watch out for that 'random number generator button' they seem to have installed on all B&Q tills, which when pressed gives you a total nothing like the amount you thought you'd bought..
'£38.95 for a pack of screws and a screwdriver!' 
)