I have a 2010 V8 HSE, the best Disco I have owned. I love this car big time.

He, my vehicle is a he because he is strong and fast ;-), recently started have starting issues.
Press the starting button, he goes through the sequence and then when pressing again it just makes the click sound. It sounds like a relay switching but not kicking the starter motor in.

Sometimes I go through this sequence 3 or 4 times and then he starts.
He will have no problem for 2 or 3 weeks and then all of sudden does it again.

I was away and left him at home for 3 weeks and the issue was there again.
At first I thought it was the battery but recently after a 2 hour drive he did it again.

Alternator has been checked by my indie, all charging ok..

How does one check the battery proper?

Or any advice what else it could be?