Not that I am an experienced drone pilot but do own a Mini 2 for personal use. You need to look at the flight restrcitions the rules change once you get over 249g (Class 0), you will need an operator license (£9 a year) and a flighers license (free), other things that come into play would be things like other anglers on the lake at the time (in some curcumstances you would need there permission before flying), is the lake on public or private land etc.. , if the pit is hit had by wind is another thing as we fish in much stronger conidtions than would be classed as acceptable to fly in, the list could go on.
With regards to the drone one with a decent camera and probably some form of polarizing filters which help take the glare off the water would help.