Hi Gary, thanks for the comments
Since moving the Tamron on I have got a Nikon 500mm f4, which suits me well BUT I don't use it handheld, very strictly either on a beanbag or tripod & gimbal, it is simply too heavy for me to consider using handheld.
In the latest of these, for example the Grey Wagtail, it was taken from a hide using the Nikon D7200 + 500mm f4 + Nikon TC 1.4II so giving an effective length of 1050mm and then cropped about 40%.
It was a gloomy day so ISO 640 and 1/1000th shutter speed - I experimentally used f10 but that really wasn't necessary and most of the day was spent at around f5.6/f6.3
I find that the 500 f4 works well with the Nikon TC's but does require care in technique.
I would love to be able to just walk around and find all of these but the time to success ratio would be very slim, I have a membership with the WWT and spend some time each week visiting their reserve at Slimbridge which always gives my a good day of photography. Aside from that I make the opportunity to visit well known wildlife sites as and when I can, so have done Skomer, The Farne Islands & Bempton Cliffs for the birds and Northumberland for birds and Red Squirrels, all of which were fantastic experiences
I also enjoy doing a bit of walkabout in towns and cities local to me for street/streetart/candid/scenes ... but not with the 500!