Keep in mind that if you ever intend to lay hardwood flooring (individual planks, not laminate)chip-board (more accurately called oreinted strand board of OST, at least here in the U.S.) is not approved for underlayment since it won't hold the nails... better to use plywood...
Ok, heathfield... we used to have particle board as well... I don't see that here anymore. It's all been supplanted by OST. The "chipboard" here was made of very small particles... almost like sawdust and wouldn't hold a ring-shank nail worth a darn...