Seedlings

Courgettes and Pumpkins will look identical, even as young plants, I expect. Pumpkins need a lot more space, when growing, than Courgettes - so might be difficult to plant them such that whichever they are will have space. Were the courgettes more leggy such that you could work out which was which?

Cauliflower and Spouts have identical looking seed leaves (like butterfly wings) so will look different to the others, but no different to each other. Their plant spacing is probably the same, so you could just plant them out and get a mixed crop? Problem if you wanted to harvest the Cauliflowers earlier to make room for a follow-on crop though.

Tomatoes will look different at first true leaf.

I would just re-plant them and carry on. Or you could re-sow them, Sprouts and Cauli are not yet late, but I would have thought that Courgette and Pumpkin was very early as yet - they will be massive[plants in pots] by the time last frost has passed, and they don't like cold at all, let alone frost which would kill them, so cannot go out "early"

Sorry, meant that everything is labelled except the Gardeners Delight (which I am guessing is tomatoes).

Do I just re-pot them all in bigger pots or can anything go outside in the ground?

The tomatoes and courgettes and pumpkins need to be kept indoors until after your last frost. You will need to pot them on into bigger pots before then though.

The sprouts and cauliflowers can be planted out when they are big enough (usually 4 - 6 inches tall) with at least 4 true leaves.

Ah.
They're about a month too early, really. I don't even sow them until mid-late April, because they grow big, fast, and can't go outside until May.

If you can't keep them above 10c and in full light until May, you might need to sacrifice them to the compost heap and sow some more.