No choke/high revs when cold

[Juicy Steve]

questions in order
1: does the CEL glow keyon (aka, SES or MIL, check engine light) service engine soon, etc. lamp, all are same, regardless of names.
2: when start engine does the CEL go out.?
3: when symptoms happen is engine fully hot, ?

Thanks for the detailed reply fixkick.

In answer to questions:

1: Yes
2: Yes
3: The symptoms go away after some driving, all though I feel like that the amount of driving is getting longer. Also, symptoms seem to be getting more profound. Used to be a bit of juddering, now it feels like fully cutting out (a bit like running out of petrol) - also, the misfire seems to stop once over 2500rpm.

Going to get the plugs out and take a look when I get chance, been a busy few weeks!