Unfortunately there appears to be no easy answer the meter placement issue.
Your DNO is responsible for meter moves, not the supplier. It'll be chargeable but they are usually pretty helpful. Get them to upgrade you to 100A while they're at it. They like doing these as old buildings with inaccessible meters are a PITA for them. An external meter mounted close to your supply point and a new set of tails running down to your consumer unit shouldn't be that expensive - although be aware that if your existing distribution board is not up to spec it'll have to be upgraded anyway, for which you'll need an approved electrician, the DNO guys won't touch it.
