Currently, I have standard white sockets and fuse plates fitted. I want to upgrade these to a decorative finish. The problem I have is several of the sockets and plates are adjacent to each other with virtually zero space in between. Major DIY stores do not sell decorative switches to match the size of standard white; there products overlap. I need to know how and where I could look to purchase replacements that fit exactly and do not overlap.

Thanks

I will assume you mean switch plates rather than "fuse" plates. I'm a little confused because you start talking about outlets-"sockets"-but then talk about switches. Are they in individual boxes? Easiest thing may be to install Old Work gang box that will fit 2 outlets. Decora and other decorative switches and outlets fit in a standard box.

I get the impression that the OP is in the UK.