Just fitted my Evohome kit supplied by PlumbCenter - their 20% off first order code (FIRSTSHOP20) got me the whole lot for my house for 421.44 inc VAT.
Product code: 312711 Honeywell evohome Starter Kit
Photo shows the old style display / wifi box and only 5 valve heads, but it is actually the newer WIFI display now with the relay boiler control box, a 4 pack of heads and two individual ones for 6 in total.

Seemed to me to be at least 50-60 cheaper than the next nearest price I could find.