Using artificial soil for sowing seeds

You can buy 'seed and cutting compost' from just about anywhere - garden centre / DIY / supermarket. I must admit tho, I just use ordinary multi-purpose compost with just as good results. Defo don't use garden soil tho - the structure is all wrong for the purpose.

Same as sid I always use multi -purpose in fact I use it for everything.

This is an interesting question as most seeds don't really need any nutrients to get started. One of the major problems is 'damping off' which is a fungal disease carried in the compost or the water used to water them.
Because of this I start almost everything, especially expensive seeds, nowadays in vermiculite. It is clean (almost sterile), conserves moisture, and the seedlings root into it very well, making them very easy to prick out and plant on. (Obviously you can't leave them too long in just vermiculite as it's got no nutrition.)
I use shallow Greek yogurt pots as a petri dish cover fits exactly over them to keep the moisture in. I can even stack them in the propagator in the spring when space is at a premium when germinating lots of things at once.

John Innes Seed and Cuttings Compost.

Any garden centre does it. Small bags for about £4-£5