@chopc it's not quite as big as it looks, we just have a small garden 
It's 5m wide and adding 3m length to the kitchen. We'll have a kitchen , table, sofas and my piano. Plus hoardes of the kids' mates hanging out.
It's quite high but once the steps (2steps down) and doors are in I'm hoping it looks more in proportion 
If not, we'll it's too late to change it.