Lavender and Dianthus should be left alone or only lightly trimmed. Lavender will not normally shoot from old brown stems so always leave some of the new green growth.
The Foxglove is biennial so leave that alone too, remove any dead or dying leaves.

I agree with the advice given.

Hi, I agree also, but knowing the ''small'' size of plants that t &m send out, I'm surprised that they have grown large enough to warrant a 3 litre pot, I would have expected perhaps a 1 1/2 litre pot would have been appropriate, especially for overwintering them, Derek.

Only further advice would be keeping these all on the dry side or they will rot over winter, especially if in too large a pot.

Just wondering why yo want to overwinter in the greenhouse? They are all hardy?

Thanks for all advice.
Stera - I have no other room other than greenhouse, don't want to leave them on grass in back garden.
The plants are all quite big now and many were becoming root bound in the original 4 " pots. this is the third time they have been re potted this year.
I will use all the advice you have provided. Thanks.

What I meant was why not plant them out?

Arr, sorry Stera.
Believe it or not, I don't actually have any beds in my garden. I generally grow them to plant in large tubs for myself or plant some of them out at the bowling green. Unfortunately when I have planted them at the green previously and people who like to help with the weeding pull them out in the spring, thinking they are weeds.
Even though I mark them with canes.

Goodness, how infuriating! See why you grow them on in pots then!