Stevia is not approved by UK authorities and not available.

I did find some rogue stevia and was not impressed. Strange aftertaste.

Splenda is a close to sugar as you will get but that is its main disadvantage. it has maltodextrin as a filler which can produce an insulin reaction and taking Splenda does little to wean one off the "sugar fix" sensation.

But I cannot drink Tea/coffee without some sweetner and have settled on Splenda now that it is available in the UK