Does anyone have a rough idea of how much it costs to have plug sockets fitted?

[Chungus]

And an old one replaced as a double one?

I've only had one in this bedroom since moving in about six years ago and it's a pain.

Thanks :)

Somewhere between £40 and £70 per socket.

depends. If its putting a second next to an existing then that's easy and cheap. If its putting a new socket onto a solid wall with no power there then you're looking at chiseling out the wall, running the cables down, replastering, redecorating etc

I would probably have a new double one put next to the single one, extra cost would be marginal and then you would have three sockets. We had a few sockets added recently with other electrical work and it was easy to add sockets near where others already were.

weve had new plug sockets put in and worked out at around £50 per plug as ours needed digging into the plaster and new wiring due to old wiring being in the skirting boards, we are in Yorkshire so don't know if prices cheaper here than say London or south

Depends on your wiring. For one extra socket you can usually run a wire from an existing socket, which is quick to do, so relatively cheap (£50 ish). However you can't (safely) take a spur off a spur, so if you're unlucky they might need to do extra wiring, which would cost more.

Changing socket for a double is also easy, so won't add much to the cost as the electrician already there.

Is your consumer unit fairly modern, we had one from the late 80s and couldn't have new sockets apart from an RCB one as our consumer unit didn't have RCD so had to get that changed before we could have sockets added, though that may have been because some were additions in the kitchen.