Thank you, all.
Sympathies over the tomatoes, Oopsadaisy1 - I must say that although I managed to avoid blight, my last two lots of tomatoes were decidedly disappointing, flavour wise anyway. Just not worth all the faff.
Yes, Casdon, they’ll need very big pots - I already have one I can use, but will almost certainly need another - I thought no more than 6 to a roughly 42 cm (internal) diameter pot. If most of them come up I’ll have to give some away.
We’re in SW London and the garden is very sheltered anyway, so planting out in April should be fine. We don’t have a greenhouse or cold frame - space is very limited.
A trip to the garden centre is looming, for pot, new compost and canes to make ‘wigwams’. I’ll have to take dh, for porter duties!
I don’t know whether any particular feed would be best. My keen gardener mother always swore by tomato food for any flowers, but if anyone’s got any better ideas I’d be pleased to hear them.