I think the GP surgeries are calling people for their first and second jabs separately, but the website booking service gets you to book both at once.

T had his via our surgery, but I still had to drive him as they are also part of a group and were doing jabs at the village hall in Islip, presumably because it's bigger. (It would be theoretically possible by public transport, as it is on the railway line, though I don't think many trains stop there. It would also have been possible to walk - about 3.5 miles each way - but as I could drive him that made more sense.)