Although the book's official publication date is in late January 2019, some early reviews are already in.
'Absolutely brilliant' - Paul Ross, Talk Radio
'Profoundly historic' - George Howard @cosmictusk
The best supplier at the moment appears to be 'Books etc'. They have the cheapest deals, for paperback and hardback (£12.91 and £17.83), and offer worldwide delivery (free in the UK). Fantastic!