Why not leave them and see what happens? I don't think they like root disturbance. You'd need to sow some more under cover, too, in case they don't make it.

Hi Jeanette agree with Spritz its good fun experimenting .

Certainly would not throw them away. However you can dig them up, carefully, pot them up and keep them for replanting in Spring. They do not need warmth, they are as tough as plants can get. The professional Sweet pea growers often sow theirs in October/November.
Better not letting the pots totally freeze though.

They should be ok left in a cold frame,or under cover.As Owdboggy has already said,they don't need warmth..just protection from the elements..and I'm sure I heard or read somewhere,to nip the tops out if they get straggly? not sure,as I have only grown them from seed in spring..but yes,the professionals use this method too..

Thank you all you lovely people for your advice, much appreciated :-)
I have potted on the ones I found sprouting between the paving slabs..I'd heard they were notoriously difficult to grow from the seeds...and here they are competing with the weeds!! (and with no assistance from me!)
Amazing to see how they sprout - and even 'righted' themselves when moved!
I have (plastic) greenhouse and cold frame so I'll move the pot in there to protect from the worst winter weather
I'll leave the ones growing in the flowerbed like you said Spritzhenry - they're in a sheltered west facing corner so it'll be interesting to see what they look like in the spring!
Thanx again everybody
jeanette :-)