Very neat idea.
It might be interesting to look at trying to visit some other countries in Europe as well.
Though the UK is clearly the easiest for this from a legal/regulatory pespective detecting is also legal in some
other European countries though the laws regarding what is done with the finds varies. For example, even in countries where finds have to be left for inspection with local authorities and then, if released, require an export permit this could perhaps be handled by any local club
members with whom the tour partners and could be sent on after.
For example, though I have never gone detecting in
Austria from what I understand of the regulations you can detect on land that is privately owned and not in a declared "archeological zone", with the land owner's permission. To be fully legal you then turn the finds in to some government office (I am not sure which). You then get them back if they do not rule them as a state find - this is apparently not as clearly defined as in UK Treasure
Act but the concept is similar. A
hoard or some important precious metal coins may be taken (though I heard from one person, a government official, that if it was found on private land and not an archeological zone then there was no way the state could legally take it) but in any event individual
Roman bronze finds will be returned unless you happen to get a
Regalianus or Dryantilla-type coin. You then apply separately for export of the coins/items.
Not completely sure of the regulations but perhaps there are clubs in
France,
Germany,
Austria, Netherlands, etc. that you could hook up with.
Combine it with (non-detecting) visits to some nearby historical sites and museums and you would have an awesome holiday.
Shawn