I've noticed these TomToms seem to be at a great price, especially after using the 10% code FREEINDEX and remember to go through Quidco for 3% extra cashback.
TomTom One UK only £137.73 after the voucher and £133.59 after Quidco.
TomTom 710 only £230.06 after the voucher and £223.25 after Quidco.
TomTom 910 only £260.49 after the voucher and £252.67 after Quidco.
I hope this helps anyone looking for a quality satnav and these seem to be comfortably the lowest prices anywhere available online, that i've noticed anyway.