Here is the next batch of seeds to be sown which include: Lettuce Little Gem, Cabbage Golden Acre, Celery Tendercrisp, Kale Black Tuscany, Onion Long Red Florence, Broccoli Di Cicco, Dill and Basil.
For many varieties, you won't need to sow the whole packet of seed all at once and you can either sow a later batch (for example to keep a supply of lettuces through the summer) or keep some back for next year. All the cabbage family seed will last for a few years if stored in a cool dry place. This won't work for seeds like leeks, onions, carrots, parsnips or beetroot though which need fresh seed each year. Unless you have a large vegetable plot for example you won't need more than a dozen cabbage plants - and a pinch of seed as seen below should be adequate while allowing for some wastage.
Please remember that the celery, basil and dill really need some warmth to get started so if you don't have somehwere suitable to sart them off now, wait another week or two before sowing them as we can still get some very cold nights.