Don't think there is any way around it, you certainly can't re-transmit the signal.
You could try this if you have a Windows 7/8 computer/laptop.
You can turn the computer into a wireless access point. Download and install Virtual Router Manager. You can then log onto BTWifi via the Windows computer and your other devices can access the Internet by going through the Virtual Router.
You can also turn the computer in an AP without the Virtual Router software if you prefer to not download software with this guide although I have found the VR software easy to use.
I don't think there is any way for the iPad or iPhone devices to act as AP without being connected to the Internet via 3G
You don't need an external Wifi AP with the suggestion I gave. If you have a PC/Laptop that can connect wirelessly with Windows 7 or 8 you just download and install the Virtual Router program and when you open it follow the prompts to set it up.
In all it takes about 5 minutes to download and install to be up and running. It is very easy to do with "No major faff". It turns your computer into a Wireless AP.
BTWifi-X works in the same manor as BTWifi so you will not be able to anything with that which you can not do with BTWifi.