Oh!
Bit awkward then. Are there any grants available in your area for help with buildings in conservation areas? Or perhaps for energy efficient replacement windows - with wooden frames?
Go back to the council and plead poverty asking them what to do considering the windows need replacing but you cannot afford the required wooden frames e.g. is there any financial help available.
If you search the internet for advice on grants - beware - I found a site that looks like it might be a government site but charges £1.5 a minute for phone advice!!! I didn't call them but I bet many people get caught out

Sorry I cannot be more help.