Paddylast,
Apologies for delay getting to this.
Yours is a really interesting case.
Index-linked is the nirvana of pension plans. So, normally, I'd metaphorically lock you in your house if I thought you were going to go out and trade in such a guarantee.
But if you need that pot to buy notional service......?
I'm second to nobody in my regard for notional service. But would I trade in an index-linked pension for one?
It all depends on the maths.
How much do you anticipate your salary will grow between now and retirement (in real terms)? How much pension would that UK pot deliver? How much do you think the notional service will get you?
It sounds like you need professional advice. But please be sure that anybody you engage understands public service pensions and notional service; all too often it seems that advisers havn't a clue about these.
Best of luck with your decision. Please let us know what you do and how you sort it.