Enlargement of a map to a big size and printing it?

 This is a problem I need help with. As some of you are aware I want to build a model railway of the Sheffield Victoria and Nunnery area in OO/HO gauge (4 mm Scale).  To do this I have to make the railway board about 10 feet wide and 70 feet long.  Where to house this is another problem, that I won't go into in this post. Now to get it as accurate as possible, I have got a map from the Ordinance Survey which covers the section. However the map I have is only 11.5 inches longs (29 cm) and 1.5 inches (3.3 cm) wide when printed to an A4 Sheet. Now if the map was scaled up to the 4 mm scale it would come out at the 10 feet (275 cm) wide requirement and I think the length would be 70 feet (2133.6 cm) about.  The problem is that I don't have the ability to enlarge the map to that size, or print it off.  I have tried scaling the image to that size without success. What happens is that the original image has space around it and it scales the space - not the image. Also because there is a curve section making the image look like a sock, I can't using the software I have cut the image away from the space. Or at least when I do the saved imaged still has space around it.  So that is my problem! 

Obviously I don't expect the image to be printed on to a massive sheet of paper 70 x 10 feet!  I was thinking that it could be printed on some of the larger sheets of paper A3 upwards in sections. 

So can it actually be scaled up to that size and then printed out in sections?  

If you can help or you are a commercial printer get in touch below. 

The image is below. As for the costs, I have a figure that I could stretch to at the present time, but I don't want to encourage someone to offer to do it at that price, when it could be done for less by posting it. I do know it won't be cheap. 

Update 28 June

I have imported the map into Templot. This is free software that allows you to scale maps to model railway sizes. It was really set up to allow you to build your own track and make your plans to construct the layout. Now it does take a lot of figuring out to work it. And though I was able to get the map into the software, if it was printed out at the 4 mm scale each piece of A4 paper would have a very block effect on the map so you would see the individual pixels of the drawing and not a solid line or shape. 

The way around this I have discovered is to simply enlarge the map slightly so it keeps the detail, but use the blue square grid of the software that divides the map into 1 foot square sections. From that you can transpose the detail onto the model railway baseboard by dividing the board into one foot square sections that correspond to the map.  This way you can see where each part of the map takes up the space. So a building can be marked off in the square it sits and measured up. 

  The above map shows the scaling down each side and more details of the surrounding area, which I won't be using. The blue lines are the tracks that you have to put in to get the map to print out in the software. 

The next map is a cut down version of the other map. It would have to a couple of feet on the upper end of Victoria Station to take in the Wicker bridge. But it looses a foot on the Woodbourne Bridge end. This makes the whole thing about 76 foot long! 

You can see a more detail section on the map below. 

This is a larger scale map and dates to 1970. Ignore the red balloon and the green track TL001.  As you can see the yellow track from the software matches the distance of the map track.  The blue squares stand out more, the the map also had grid reference squares which show as grey black lines. 

The scaling of these maps helped to find the kink in the track starting position. Up to that point from Woodbourne Bridge the boards would be standard width boards. I have yet to decided on the width of the layout. I think I could get away with an 8 foot width. As I would have to have a strip down the side to get more in. Most plywood sheets come in fixed sizes, so an 8 x 4 foot, if they were laid along the straight section, that would use up 14 boards. I think that would be better than having them laid along the section in two's, thus avoid creating a join along the middle of the layout. As the layout is full of different levels. The plywood could be as little as 5 mm thick. Since no track will actually be at that level.  The final kink section would take another 5 boards.