I try to refer to them as aircraft or UAVs both here where we should all be enlightened about “drones” or on social media where the commenters are deeply suspicious of the noisy, dangerous, privacy-invading burglar tools.
As to where to fly - there is a lot of (correct) information on the Dronescene Map. The information comes from various sources - CAA, Crown Estates, National Trust and, for recommended flying sites, reports and pictures from GADC members.
Although there are a good number of sites shown it is by no means an exhaustive map. There are plenty of excellent places either unreported or unflown - as yet. Feel free to add to the map as you discover fresh sites.
Basically National Trust, Forestry England and some local councils do not allow take-off and landing from their sites and also claim (falsely) that the airspace above is private. The Crown Estates, who own a lot of land and a fair amount of the UK foreshore are happy for you to fly as long as you keep within the Drone Code.
I’ve always found that if you look like you have a right to be there, smile and be friendly to those who show an interest, no-one will challenge you directly - they might moan on Facebook later!