We have just joined RingCentral and would like to change our number to a UK non geographic number

We have just joined RingCentral and had our account set up today. We have been given a new telephone number, however we would like a non geographic business number. In the UK these will start 03 or 08 and we would ideally like a list to pick from. I'm unsure how we would go about this and need help so that we can begin using RingCentral.

Thanks

George