Without seeing it, it is very hard to tell, your description could be of most consumer units in the country.
Is the 'grey wire' plastic or rubber covered?
If rubber, start saving for the rewire, as rubber persihes in abour 25 years, and they stopped putting it in 30 years ago
Do you have trips or fuses - if fuses the installation is probably more than 10 years old - not necessarily bad, but a good indicator.
Do you have an earth in your lighting wiring - you'll have to take off a light switch to look for this - is there only red or black wire or is there a bare or green/yellow one going to the backbox or switch. If no earth the house predates the late '60s, and although not as serious as rubber, this is still an indication of an installation that will need attention in time.
How many fuses/circuit breakers do you have - generally later installations have more segregated circuits, older ones may have as few as 3 or 4.
To be more specific, we need all these details, and ideally that picture. If it does all you need, and looks reasonably modern, its unlikely to need a full re-wire, but it might still be a good idea to get someone to quote you to give it the once over (professionally called a 'periodic inspection report) if you are really worried.
regards M.
