Contact me if you are interested in this seriously . If you can acquire the local UK lines and access numbers, I can give you the IVR system complete! You will only need to install a gateway capable of handling the number of lines that you need and the appropriate bandwith to route those calls to the internet. Figure 30K per cal MINIMUM.
I work with a carrier that has a European server.
Estimated cost of a low cost compatible SIP device is ABOUT 3000 Dollars US, maybe less.