As ever, thanks for the replies, it's always good to get forum advice.
My car must be set to flexible servicing rather than the fixed, hence the 16k without any work, but it was delivered that way and I'm happy with that. From what you're saying it sounds like the 'inspection' should not be counted as a 'service' under the plan and I guess I'll pay for that separately, thus retaining the second of my paid for services for a while yet.
I'll book it in for the oil service ASAP and will report back when the service schedule is clarified.