At the moment i believe only ee offer the cellular sim- id possibly like the option to use cellular In the future but i am currently tied to O2 until July so wont be able to use this feature?
Otherwise am i better off just buying series 1 - not much monthly difference though money wise.
I am assuming you have an iPhone. The non cellular 1, 2 or 3 is essentially an iPhone accessory, and no use as a stand alone product.
Don’t buy a 1, the hardware is already out. Either get the series 2 which is much better hardware and then upgrade to a cellular (or 4) at a later date.