No water cock in the pavement that I can see, no water in the garage, and yes, patio and then tarmac across to the garage :S
The accumulator idea is well worth bearing in mind if I can't get the cold water flowrate I need off the main without rework.
At the end of the day, I don't want to go overboard, but I would like to be able to run a shower and have a hot tap turn on elsewhere without everything turning into a dribble - i.e. be able to satisfy a transient demand peaks without really noticeable adverse effects! Seeing a friend's 28kW boiler service a shower and then turn the hot tap on in the kitchen was just totally unacceptable to me - poor performance at both outlets instantly.