I've just setting up house here in Phuket and am looking for somewhere that I may be able to buy Sheridan Bed Linen....

Is there anywhere in Phuket?

Check out a store called Penang, right opposite Supercheap. They have all bed articles except for those to be found in Soi Bangla.

I agree, their linen is first class and same as used by sheraton, banyan tree etc.

first class, not cheap but good value if you like quality.