Far too early to plant out even in London. The tubers need to have been kept dry and frost free over winter, so if you can take them out of the pots and put them in trays covered in sawdust or wrapped in newspaper and kept somewhere suitable, that woujld be best. OR. put the pots somewhere safe. Plant out in the garden when there is no longer any danger of frost.

If you haven't got any sawdust very sdry comjpost will do, just as long as they are kept dry. Keep them somewhere that mice can't access. The little darlings are quite capable of nibbling an access hole into a wooden shed!(so I discovered...)

I wasn’t sure how the thank you worked .Thank you both very much re the dahlias! Let hope you receive this ok.

As you are in London, I'd do what I do [Hampshire], just stand the pots in a sheltered place, maybe against a wall.

Frost is unlikely to be a problem given your location, damp / wet will be the killer, hence a bit of shelter against a wall

Or, lay the pot on it's side until Spring, then plant out in garden once growth starts

You will have to watch out though, slugs love young tender dahlia shoots, get your protection handy now

I used vermiculite as a bedding material for bulbs and placed them in shoeboxes (not plastic containers which are mouse proof but not mold proof) I kept for that purpose. I would check the boxes periodically for mouse scrapes, if so, I placed poison bate in the vicinity which was very effective.

Thank you allot your advice about the dahlias. I think there are a few ideas there.
Pat