Modern dwellings have higher load on the electrical system than years ago, so if you have old wiring drawing a heavy electrical load, it's potentially a disaster waiting to happen.
Even if the safety issues weren't bad enough or if you're intending to sell your property, you'll have to get the electrics updated before you can sell. Very few mortgage lenders will lend money on a house that is a potential total loss!
If you have concerns about the wiring in your home, it's imperative to have a qualified electrician to check it out. This is not a job for a DIY'er. Under the IEE wiring regulations, there are strict rules on the jobs that you can do yourself. These include replacing existing sockets, switches and ceiling roses, individual cables or flexes, adding lighting points, sockets and fused spurs. Exemptions include if this work is being carried out in a kitchen, bathroom or outside.