I don't think there's 100% foolproof deterrent for anything but I keep my hostas in pots/tubs and they get very little damage.
I've heard some people put vaseline around the rim of the pots to stop slugs climbing on to the compost but I would find that too messy so I just put up with the odd damaged bits, and they're hardly noticeable actually.

Not in pots I’m afraid I have two in the ground.

I would dig them up and put them in pots. They will only get eaten by slugs if grown in the ground.

Okay, thanks folks.

I would suggest that for the present I would replant in pots. But in the long-term perhaps think about growing something else. I love Heucheras but was plagued with vine weevil so gave up as a bad job.

Molluscs here don't really eat the Hostas (and we have a lot) until late in the season, so we just ignore the damage as the leaves will be removed fairly soon after that.
The garlic spray is as effective as anything else and at least it is not harmful to other things.

Your answers are much appreciated folks.

Copper rings for hostas grown in the ground
https://www.greengardener.co.uk/?post_type=product&s=copper+ring

Having seen the size of the slugs around here, I’m not going to grow Hostas (don’t hold me to this!) :)