I worked for a call center in India for almost two years, the no. of line requirement will depend on your customer, if your customers are based in UK only, then you need to apply for a toll free no. from your Telephone authority that will enable your customer to call your no. free of cost. You wont be requiring more than one line. The call flow can be handled by a software called as Call Manager and it assigns the incoming calls automatically to the Call Center Agents depending on their Idle time.
You need to have a server so as to load all the da
ta related to your business at one place and accessible to all your agents (your agents will need a PC to keep track of your business :). If you are doing business on the internet then you will need a Router or some Firewalls for security reasons. Let me know If you want to know anything else.