Spark Pug replacement interval

Can someone advise me please at what mileage intervals it is recommended to change the Spark Plugs my 2014 1.0 VTR ?

Also what should the electrode gap be?

Thanks.

No-one knows the answer?

There is no replacement interval for spark plugs. They are to be inspected and gapped every 20,000 miles (30,000Km) when you do your regular servicing. If the centre electrode wares down to about a millimetre (typically they start off at about 2mm) , then replace them. The gap for "standard" plugs is 0.9mm
If you want to save the effort of servicing your plugs, buy Iridium plugs. You only need to inspect them every 60,000 miles and if the gap is too big just replace them, you cannot gap these plugs. The next best is Platinum, for similar reasons. Because these plugs produce a better spark you can get a very small gain in performance. The prices of these plugs are coming down and if you look around you can find them for nearly the same cost as standard plugs.
I also recommend using an anti-seize compound like copper grease. A steel plug into an aluminium head is not a good idea. Don't over tighten them either. Torque is 25Nm or 18 ftLb.

Thanks for the reply. That is exactly what I wanted to know!
My car has currenly done 35,000miles and I believe the plugs have never been out or changed so I think it is probably time to replace or at least have a look at them.

Thanks again.

You can tell a lot about the condition of your engine from the plugs.
Under normal conditions they should all look the same and have a thin, dry, dark, sooty dusting on them.
If they have a light coloured crust on them, there are impurities in the fuel or oil (most likely fuel).
If there is a dark pasty build up, that will mean the engine is burning too much oil. All engines will burn oil, it's just the quantity that matters. Of course you will see that with the dipstick too (I mean the level will go down).
With modern cars the engine management unit keeps an eye on under and over fueling so you won't see those signs on plugs much these days.
When you put the plugs back in be very careful not to to cross thread them. A handy tip from the Hanes manual is to use a short length of garden hose on the plugs. This extends the reach into the head and if the threads cross-thread, then the plug slips in the hose.