Agreed but if the OP isn't confident enough to do it themselves then it certainly makes sense to get someone else to it.
Not all sockets are straight forward though. For example, on a number of occasions I have had to pull the back boxes out and fit deeper ones and them make good because the customer wanted flush plates.
The job is so small that you are going to have to expect to pay for a minimum X hours, which is fair enough because whoever does it will need to factor in travel times, which may well be longer than time spent on site. With such small jobs I normally recommend that the homeowner try to bump up the amount of work so that you end up employing someone for half a day, or a full day. That way, the travel costs are lower than the time spent on site.