Was talking to a friend about this and I actually don't know! The community midwife office is only open weekdays 9am-1pm, and even then you usually can't get hold of anyone. 'My' midwife at the surgery is always too busy to answer her phone and the GPs as a rule 'don't deal with pregnancy' at our surgery. The obstetrician said 'if you have any problems before the next appt, call' but again only 'office hours'. And would you actually get to speak to someone? So who would you speak to? Midwife on the labour ward? Someone from the birth centre?
I've decided to go for a private scan I think to check growth as I doubt I'd manage to convince anyone that bump should have grown in 4 1/2 weeks and would rather be safe than sorry (it's only £100 - worth it for peace of mind!), but again - who would I call if there WAS a problem????