Christmas gifts (sorry!!)

English Tea and a very nice small china teapot/mug. They come in a box so would pack well.
English lavender hand wash/soaps etc.
Linen e.g. tablecloth/napkins

Bit difficult as you cant take food items or seeds/plants in I think.

I have family in Australia. There are so many restrictions on what can be taken into the country. May I suggest you Google the list of restricted items before buying gifts.

Handmade soaps are lovely. Dd gave me some one 🎄made by a friend - gorgeous creamy lather, so much nicer than anything from a shop.
Might be nice as long as they don’t just use shower gel/hand wash in a bottle, but a lot of people nowadays are trying to cut down on plastic.

You're taking yourself, what more do they need?!

Agree with ali .

If they have a link to a particular area of Britain then maybe begin by thinking of anything traditional linked to there. National Trust on line gift shop might be worth looking at and the garden centres are full of gifts now. Soft, hand crafted items are easy to pack. If you’ve time something personalised from Etsy or similar. Sorry. All out of ideas now.

Seriously, don’t worry, surely they will just be pleased to see you.

Cornergrans idea is good about links to an area maybe an ancient map of that area could be an interesting gift and very light.

Sorry if this is Victor Meldrewish but what has happened to the word ‘present’? Esp re Christmas where we surely give presents, not gifts.
Have a wonderful trip, OP. Lucky you. If the family includes children how about something London-themed?