You might add Corsican mint to your list of choices too. It does need moist soil with good drainage though so if your patio faces west, there might be a problem with heat and dry conditions.

Internet search for 'plants to grow between paving' (or similar) will give you more than enough suggestions. As with most gardening, your final choice will depend on aspect and soil type (and how much traffic the plants will have to put up with)
Mind-your-own-business is great if it's a cool shady paving with a tendency towards year-round dampness. While thymes prefer somewhere warmer.
As for buying seeds in one place, you're probably better looking at the major companies such as Suttons, Mr Fothergills and, even T&M. Or visiting a local garden centre.
Also consider plug plants and small rockery pots such as Sempervivums, sedums, campanula and don't forget good old moss!

I did this last year and liked the Thyme, but found the Chamomile got too big. This year I've added tiny Violets, and that seems to work. (I like Seedaholic.com as their packaging is beautiful(!) and they give so much useful growing information.) Good luck :)

Thanks for all the suggestions. I suppose I shall have to wait until next year to plant the seeds?

We had viola seed the path around the tub they werein and flowered late summer....
I like to see Campanula, its a lovely blue...

You could be just in time for some seeds to be sown in situ.

If you have plenty of seed, why not sow half now, and save the rest for next Spring? Definitely worth a try for this year.

This started me thinking about the paving planting for my yard after I've re-paved and I found a great list at http://www.independent.co.uk/arts-entertainment/gardening-get-cracking-for-the-cottagey-look-pristine-paving-is-out-michael-leapman-searches-for-lowgrowing-greenery-to-spread-among-the-stones-1540624.html

Sorry it's such a long url, but it gives plants for sun and for shade, for cracks and for pockets - and it explains what to look for in plant growing habits (and recommends a specialist nursery) - I've just fallen in love with Mazus reptans.

Thanks so much for all the help.
Urbanite, I have read the article, and will definitely follow it up, thanks.

Thanks for that article, Urbanite . . . I have printed off the section for sunny areas of paving, for useful future reference :) (And Mazus reptans does look lovely!)