I was thinking of planting the Bearded iris tuburs directly into the garden rather than starting off inside in pots

It's fine, you can plant them now if the ground isn't frozen. The rhizomes are dormant now. Be careful not to bury the rhizomes and that they are exposed to the sun and air. They should lay on the surface with only the roots buried.

Mine are always in the ground so plant them out.
Have you bought them as bare root specimens? if yes they need hardening off first, so pot them up in a few inches of compost, rhizome horizontally on the surface. [I do have a friend who buried the rhizome like a carrot vertically as she thought the green leaves were bent from being in storage. But as she said she hadn't seen them growing before] then pop them outside during the day and indoors at night for at least a week. if it remains mild then plant them out then. don't worry if the compost drops off them just bury the rhizome a little into the ground. ideally over half of the rhizome needs to be above soil level. They do best in full sun without lots of other plants crowding them out.

I’ve just planted some. They should be ok. They are very hardy. As long as they have excellent drainage, and the tubers are mostly above the soil they will be fine.

Lol..so true!

If the ground is workable, then just go ahead and plant them. They may even send out a few roots to nourish the rhizomes which they need while dormant.

Mine are starting to shoot forth. I noticed a little green. Good luck!