That's a very useful document that T found for you.
Suggest you speak to your line manager ASAP.
It is the job of the company that has won the contract to liaise with your company, and speak to you about what happens. The new company is obliged to take on responsibility for your employment - which transfers to them under similar terms. The main parts of your contract (pay, hours per work,) should remain unchanged (initially at least). And you should expect that you continue doing the same job at the same site, just that your employer is different.