There was a surplus of food following the agricultural revolution. People could be fed at lower prices, and that extra money could be used to buy manufactured products. Additionally, when people are well fed, they can be specialized into jobs that aren't farming.
Large increases in population also helped push the industrial revolution forward. Factories required lots of people working in them. There was a very large population that could be employed into manufacturing jobs, which gave factories the ability to operate.
Britian had a vast supplt of natural resources that were used to power industrial macheinery. One of these is coal, which powered steam engines. Also, a large supply of the mineral iron allowed for the manufacturing of steel.
The financial situation in Britian also helped cause the industrial revolution. Entrepeneurs were interested in taking risks, which pushed industrialization forwards. Furthermore, financial institutions (such as a central bank) financed new factories, basically subsidising them, gave the factories a boost to get started.