Training a new grape vine in a greenhouse

I'm not sure how you'd do it in a greenhouse setting as I've grown mine outside and as you mention. But if you can get hold of the book of the old telly series Victorian Kitchen Garden for fruit and vegetable growing, I believe they cover it there as the old greenhouses used to do it the way you want. Other than that, find an elderly Italian veg grower who will have done it all his/her life and can advise you.

Very useful, thanks.  So I will let it ramble along some selected leaders this year, prune them back to a pencil-thick point, and allow leaders to grow again, and prune back, for the next two years.

I will remove all laterals for the first two years, and all grape bunches.  In year three I should be able to allow laterals to grow and bear fruit.

The leaders will be along the house, and the laterals across/vertically.

I'm inclined to grow three leaders - one at the eaves, one at the ridge, and one in the middle - but maybe a single leader, in the middle would do? and I could then take laterals off that - up and down. (or maybe a leader at the Eaves would be easier because the laterals only need to grow up

They refer to the variety I have as follows "BLACK HAMBURG - The original gardener’s grape – fantastic for lots of good fruit, if grown under cover" which sounds exciting

Very useful, thanks.  So I will let it ramble along some selected leaders this year, prune them back to a pencil-thick point, and allow leaders to grow again, and prune back, for the next two years.

I will remove all laterals for the first two years, and all grape bunches.  In year three I should be able to allow laterals to grow and bear fruit.

The leaders will be along the house, and the laterals across/vertically.

I'm inclined to grow three leaders - one at the eaves, one at the ridge, and one in the middle - but maybe a single leader, in the middle would do? and I could then take laterals off that - up and down. (or maybe a leader at the Eaves would be easier because the laterals only need to grow up

They refer to the variety I have as follows "BLACK HAMBURG - The original gardener’s grape – fantastic for lots of good fruit, if grown under cover" which sounds exciting

That's the variety we have, Kristen and it is very good indeed  I have trained a leader along the eaves each side and one along the top, and keep it well contained by hard pruning each autumn --- you know where to cut back to because you have to cut into brown wood not green stem,as the ripe wood is where the fruiting buds are. I don't have the space you do as my green house is only 8ft long though

Just a note of caution though -- it does spring into growth very early each year and the new leaves can easily get badly scorched if we have a sunny spring. Mine has lots of burnt leaf edges this year. Something to consider as you are planning ahead.

Hope it goes well