Hi - looking for some advice . After putting key into ignition and turn to get light cluster on dash I tried turning the car on - nothing for about 3-5 seconds ... then the car jumped into life just as normal. Turned key off snd tried with spare key ( just in case ) - same problem 

After driving and stopping with warm engine - same again - it’s almost as if the engine “waits” a few seconds before jumping into life. (Battery replaced about a year ago and car is run every day). 

it starts up quickly, not a slow turnover into life. 
Q7 automatic - 3.0l diesel

Any ideas ? 

The first thing I'd check is the battery, if get it checked to see it's performance as a failing battery can affect a car starting. The normal life expectancy of a battery is 5-7 years. Halfords can do a battery test for you. 

If battery is in good condition then I'd look at the condition of the glow plugs for their condition.