Bill not a source, but personal experience which might help.
I'm located approximately 52° 20' N and 09° 40' E. I am using a 110cm
Triax Dish with a quad LNB chosen for best results on my SatLink meter
(strength and S/N), not lowest noise factor!
When Astra 2D was still aoround things were fairly good regarding the UK
spot beam. Since the change to Astra 2E, F or G - I have lost track
which is used, the UK spotbeam seems to be considerably tighter.
At this location, reception is generally OK but there is no margin for
losses (caused eg. by bad weather) at all. Additionally, the signal
deteriorates in the evening going as far as losing all reception of the
UK spotbeam. This is sporadic and annoying when viewing one of the few
programs worth watching. First of all the sound splutters, video starts
to pixellate and within a few minutes - nothing
Initially I was thinking of upgrading to a 150cm dish to give me 2-3dB
more margin, but recently, considering how UK TV (which I for a longtime
considered to be among the best) has gone downhill, nowadays BBC1
generally only shows dross, I don't think I'll bother, relying more and
more on my PVR recordings.
I know that moving further to the east reception drops out rapidly, so I
consider myself to be on the very edge of the footprint. The same
applies when you go further south.
Just my twopenny worth.