Blacking - if you hire a dry dock, some are charged by the day so summer is best for the minimum time on the dock (on in the morning, pressure wash down, one coat of black on in the afternoon, another the next day and off the following day)
If you need to know about TV, try contacting Travelsat who seem to have more satellite dishes on boats than anyone else
http://www.travelsat.me.uk/
I reguarly use a 3 dongle to access the internet around the system and the only definate 'black hole' is Great Haywood but I'm sure there are others although remember line of site is required to get a signal. There is s a link below to a canal and riverside pub guide where I am capturing all the pubs/places that have wifi where large files can be downloaded and backups to a cloud can be made. If you find any others, please let me know for the benefit of all