We'd go and visit the tower at Quex Park in Kent and see inside it - it's actually a bell tower - and also visit a local museum (nothing to do with the series, but a local fan says it's well worth visiting.)
2nd or 9th September currently seem the best bets. They're both Saturdays and most people should be back from summer holidays by then. I'll pick the date that works best for those interested in coming.
All welcome - several people have already expressed an interest, so you won't be alone <smile>.