Claire,
I think it varies according to church. Presbyterians, and particularly Scottish Presbyterians have always had a very high regard for education, and it was almost a mantra of the Reformation that every Minister ought to be his own Theologian. some churches train 'Priests", we "educate ministers"
There is also a lot of vocational training.
The ministry is not so different to other traditional professions: Ministers needed an arts degree before they could study theology, lawyers needed an arts degree beofe they could study law, Doctors needed a MB before they could study their ChB, Architects needed a degree in building science before they could study design (or was that the other way round?)
More and more nurses are graduating with a Batchellor degree in nursing and then taking a Masters. I know one Theatre ChargeNurse who has a Batchellor Degree, a Masters Degree and a PhD. I often wonder whether the surgeon calls him "doctor"
Andrew