Need ideas for a useful housewarming gift

[Lottapianos]

Going to visit a family member's new house in a couple of weeks. They are a couple in their 60s who have everything they need, and I have no idea what their colour scheme is or what their taste is like

Any ideas for something nice / useful that I could give as a housewarming gift? Maybe just a good bottle of booze? Budget up to £30. Thanks

Garden centre voucher that can spent on any number of things including the cafe/restaurant, plants, ornaments etc?

How about a David Austin rose bush or potted plant?

Or if they aren't into gardening then how about some lovely slippers

DH and I are similar ages and we really don't need 'stuff', and we have our own tastes in what we'd like.
If you know that they drink, then a bottle of something would be a great idea as I'm sure they'll be receiving lots of visitors + Christmas is looming.