Thanks for all your input and advise,guys.
I will go the least difficult and most cost effective route first and will do the cleaning atc as suggested by Techno.The car is due a full brake check and other bits in the new year and as this can be done indoors and under cover I will suggest to my mechanic that we undertake a compression test just to see what results are from each cylinder as would be usefull info aswell.
The problem is evident every morning when car is started from cold and this was my thought pattern regarding the temp sender as I understand that this sends a signal to ecu for fueling until the car warms up and then the lambas take over.
This morning the car started first turn as always,but temp took about 5mins in slow traffic before gauge started to register and all the time tickover was erratic with needle moving from 500-750+ and engine feeling very uneven.When the gauge started to move upto 90 and beyond this completely went and the engine ticks over very smoothly,with it now registering mid way on temp gauge (95) and silky smooth tickover.There is no oil loss or usage and the performance from the engine is so good that I have no hesitation in keeping a wonderfull 10 year old car,and relying on it daily for my 100 mile a day job.
The problem is not major,merely of mild concern (well atleast at the moment..I hope).