Just in case anyone is intrested I ended up going down to Halfords and testing a few units and ended up going the garmin route. Seems a nice bit of kit nice and easy to use.
Things that conviced me over tom tom.
Has an sd card slot on the more basic models for adding maps. Tom Tom you have to buy the posh widescreen ones to get that. Found out when I got it home you can view your digital photos on, bit of a gimmick but quite cool.
Battey life is a lot longer so if travelling in mates banger with knacked lighter port it can be used.
I've had a garmin for walking for years and has been ultra reliable, so quite like the brand.
When booted in halfords found saterlites from further inside the store, tom tom we had to go to the door.
Bloke in Halfords said they had a lot more tom toms returned over garmin units. Wasn't any more expensive so dont think he had an agenda. Also told me not to buy the usb cable from them as I could get it for 1/4 on ebuyer which was nice.
Things that are annoying
The on screen keyboard isn't qwerty, its abc, when playing halfords assumed I could change it but you cant.
Would be nice on 4 lane motorways if it gave you more then a mile warning for turns offs, but is more then enough most of the time.
Maybe over zealous with mobile speed trap locations, flashes a fair bit, but yet to see one. Still better safe then sorry I guess.
