Any recommendations?

There's a Gardener's Question time list of plants that listeners have found relatively snail-proof. I'll post the link below but it is not infallible, and that's why some of the plants are starred. Helleborus niger was on the list but when I planted some out, they were all but gone within a day. I also note they put Marigolds and I wish they'd been more specific. I have no trouble with Calendula but when I've grown Tagetes they were all bitten off at the stalk.
On the whole I seem to do ok with several on that list, though.

As Lori says, the GQT list of snail-proof plants is unreliable. From memory, I think honesty is on the list, and I find that virtually impossible to grow.

It obviously varies a lot from one garden to another - my pulmonarias are fine, for example (they grow like weeds, actually).

The only advice I would give (well actually I could give lots - but I'm sure you've heard it all) is that it is well worth putting plants in the ground as big as possible - grow them in pots in a safe place for as long as you can manage before planting them out.

Oh, and buy a head torch - it does make catching them at night so much easier. It is a real hassle in mid-summer when there is no point going out till 11 p.m., but at this time of year 9 p.m. is fine.

Then she started buying zoo compost - camels and llamas and such. After about three years of liberally applying it in the garden the snail population seems to be down to manageable numbers.

Now, she complains about the chickweed... but that's benign by comparison. ;-)

Epimedium seems to pretty durable. Petunias can be quite robust. Dahlia and Pelargonium. Gerberas and perennial Dianthus. Some of the Geraniums and Erodiums. Iberis and Erisymum. Gaillardia and Verbena. Well, that's what we found to do better than survive.

I've had snails attack every plant list by various people here (except the Gaillardia and Musa which I've never grown). Anything that grows in moist shady spots is obviously at risk but they will also attack the succulents in the driest stoniest spots in my garden. Marigolds have to be their favourites, they are guaranteed to be stripped bare within 48 hours of planting without protection.

I'm curious about the yellow Meconopsis, which one is that? M. (=Cathcartia) villosa? Or something rarer. I find the slugs love the fresh spring growth on Meconopsis but tend to leave them alone later. You'd think those bristly leaves would not be palatable. This year they've kept munching right through summer though.

My main approach has been to grow plants which are vigorous enough to outgrow the attacks, anything else will ultimately succumb. A few more idea for you though. Lamb's Ears and similar grey hairy plants don't seem to be attacked too badly. Brunnera gets munched a little but not eaten down to ground level. Snails love to hide in my Holly, Lavatera, Buddleia, and Berberis bushes but don't do them a lot of damage. Daphne are barely touched, too toxic? Euonymus don't appear to be eaten but might just be growing too fast to notice! Native Geraniums the same, either not much damage or they outgrow it before I notice. Last but not least, Saxifrages, maybe too much like eating eggshells?

(2) Even toxic plants are vulnerable, e.g. foxgloves. Presumably these are not toxic to molluscs. Or maybe they are, and the slugs and snails don't care? After all, humans drink alcohol and smoke cigarettes.

(3) As a very general rule, shrubs are less vulnerable than perennials and annuals, presumably because they don't have soft growth at ground level, which is what slugs and snails like best.

Does anyone know whether they are partial to lemon verbena or anise hyssop, as I was thinking of adding these to my herb collection next year?

One annual which appears to be ignored when grown from seed is Nigella, as well as the antirrhinums already mentioned (they may have eaten one or two at the two-leaf stage, but not subsequently).

Sarcococca seems to be snail-free, being woody.

Sedum 'Herbstfreude' mostly just get the odd nibble but but I bought a small S. spectabile 'Brilliant' this year and they defoliated it completely. Still it's coming up from the base so fingers cross it will grow enough to establish. When I put my Agave americana out for the summer, thinking it invulnerable, I found they sneaked past the thorny leaf edges and hollowed out the lower leaves. I've noticed that they seem to sit on Cordyline and Iris foetidissima and suck on the leaves too, as they get disfigured slightly but usually no holes - probably too fibrous to bite through.