Yes but sow them soon.

Wallflowers are biennial, which means you sow one year for flowering the next. Unless there is some variety that actually works like an annual, you will have to sow now to make strong plants which will flower next year.

Agree with Bertie wallflowers sown now will flower next year. Whilst viewed as a biennial you will find that some will keep going for several years but may get leggy and scruffy.

Sorry I misread the question. I meant you can plant out in autumn but they won't flower until next year

They may not germinate in the ground, very few seeds have this year in some parts of the country.
Best to sow them in a trough where you can keep them damp.

So if I plant them out in Autumn when about next year do they flower and do they last a while and do they like sun or shade?

Mine are just going over

April to May is when they tend to flower.

Ok thanks again :)