As you say smoke/steam is coming from front grille area, my money is on a small crack / pin hole in the rad plastic casing . I had a very small coolant leak & smell of coolant when hot ,for ages but just could not locate it as no visible trace or drips. .
Eventually on a very cold day with the car at full running temp there was a small column of steam rising from the n/s front of the rad . Still could not see where it was coming from until rad was removed .
Once you are able to open your bonnet & then remove the black rad cover/s , if you can see steam from the grille with the bonnet shut , you should be able to see where it is coming from.
visible steam at this time of year ( warm) could mean it is a fair leak .. Your header tank level will give an idea. But don't forget that small coolant leaks quite often only happen under pressure when hot & evaporate before being able to leave a drip on the ground etc.
New rad is about £45 & fairly simple to do . .all be it fiddly
HTH