I would be very surprised if the heatsink didnt come with some half decent TIM. Unless you really really want arctic silver 5 it's just an added cost.
I'd consider dropping the TIM and pick up the G.skill ripjaw memory instead of the OCZ gold. Yes it's £10 more but the ram timings are lower (better) plus with the TIM gone it's only technically £5 more on the final bill
Is there much of a difference between the G.Skill Ripjaw RAM and the OCZ Gold RAM?
I'll try and find an unboxing video of that cooler on youtube to find out what TIM it comes with. Im not dead set on Arctic Silver 5, i just heard that it is very good.