You need some thread, a pair of scissors and some fabric! And an iron and ironing board. And somewhere to set up your machine where it's light and you are comfortable.
where I live there are several markets with stalls that specialise in haberdashery (there's a word that should be used more!) and fabrics.
There is also Abakhan who have branches all over the place.
Jaycotts of Chester do mail order and there are loads of online shops selling fabrics for patchwork, often called 'fat quarters'.
Hobbycraft supermarkets are useful if you have one nearby, again lovely patchwork fabrics.