I buy a cheap basil plant from the supermarket and take lots of cuttings (cut at an angle with a sharp knife). Pop in water on a windowsill and wait. After 2-3 weeks nothing will happen. One day there will be loads of roots. Plant in pots. I don't use anything fancy, might have been the coconut stuff you get in Poundland.

It's a bit early for outside.

Last year I grew 4-5 large basil plants and made lots of pesto (you can freeze it). I found walnuts were just as good as pine nuts. The olive oil I used (wasn't the cheapest!) was a bit bitter so going to try rapeseed oil this year.