Hi there and welcome Donna
It appears that the recovery partition or image has been removed if when doing ALT + F10 at startup it asks for the disk (this is a default message when it is gone, it does not actually check if there is a disk drive).
Please do not shoot the messenger, but as there is no image of windows on the computer, your only options are to locate a windows disk (so you could borrow one from a friend) and install from this. Else you would need to pat the £70 to Acer. Unlike Toshiba, they do not have it for download and charge for it.
These are the options you have sorry as there is no image available to you to do the reinstallation, so you need to obtain one.
But the £70 will be more cheaper then having to purchase a windows disk though. The issue is you need the windows installation in some form.
If you would like any additional information or assistance, please do not hesitate to let me know.
Else if you can take a second to rate my service by clicking one of the stars at the top of the screen then submit, that would be greatly appreciated.