Help me be polite

[Babycote]

I'm not from British culture and struggle with the indirectness required to be polite here. Can you please help me?

For the past few years MIL has got us an English Heritage membership which we have never used. She's now asking us if we want it renewed. I don't. How do I say this without being rude?

In my own culture I would say: "No thanks, we never used it in the first place. Don't waste your money." I understand that this is rude in British culture so what do I say?

(In the past I just said 'yes' as I couldn't figure out what to say! But it will go on forever if I don't stop it)

That's a lovely thought and we really appreciate it, but I don't think we'll get out much to the sites this year so it's probably best you save it for now.

Say something along the lines of 'Thanks so much for the offer MIL, but we never got the chance to use it as much as we'd like, so it would be a shame to renew it and go to waste again'

Nothing at all "rude" there, though I'd probably cushion things slightly by saying that you haven't got much use out of it, or similar, rather than that you've never used it, which some might say is needlessly honest.

Is there anything else you need? You could dodge it by saying ‘actually we do fancy a change and are finding ourselves spending much more time doing x lately’