If you are considering hiring a handyman for simple electrical work, you need to be aware that since January 2005, it is a legal requirement for all work on fixed electrical installations to comply with the UK standard BS 7671:2008 (The IEE Wiring Regulations 17th Edition). There standards apply to all work in or attached to a dwelling. All electrical work that includes new installations, re-wires, and the installation of new circuits; is notifiable (i.e. must be reported to to a local building control body for approval unless carried out by an electrical contractor registered with an authorised competent person self-certification scheme).
Other notifiable work includes additions to existing circuits in kitchens, bathrooms, outdoors and in other special locations. (special locations effectively are any rooms where exposure to water/damp is likely). But not all electrical work needs Building Regulations approval, if the work is minor and does not involve complete new circuits, such as replacing socket-outlets, switches and light fittings (as long as not in a special location such as a bathroom).
So a handyman can do simple electrical jobs like replacing sockets and switches, as long as new circuits/wiring is not required and not in a bathroom or other special location. But if you are in any doubt, seek advice from a qualified electrician registered as a competent person. In any case, any electrical work carried out must comply with the IEE regulations BS7671.
If having a socket or switch replaced, ensure the handyman follows the manufacturer's instructions exactly. Fitting a new socket is not notifiable so therefore it is not necessary to have the work done by a qualified electrician, nor do you have to inform your local authority building control, unless in a special location. But even if using a handyman or fitting yourself, the socket must still be fitted in accordance with local Building Regulations. If there is any doubt, consult a competent person registered with an electrical certification scheme. Even though replacing a socket is fairly simple, you must ensure the handyman is up to the job, never take risks with electrical safety.
Before any type of electrical work, you must switch off the main power at the consumer unit and isolate the circuit by removing the circuit fuse and putting in your pocket to avoid accidental replacement by another person. For additional safety you should always attach a note to the consumer unit stating you are working on the circuit. Then the circuit you are working on should be checked using a voltage tester/meter to ensure it is not live. Make sure any handyman you hire is aware of the necessary safety requirements when working with electricity, if possible, check with previous customers that have had similar work carried out for references. A good, experienced handymen should be able to easily do any non notifiable electrical job, including replacing a single power socket with standard white double socket, putting in a new light switch changing a fluorescent tube, or installing light fittings and fixtures using existing wiring.