I am in a hotel with wifi. The way it works is that each room has its own username and password and you can't have more than one device connected at once.

This is a bit of a problem as I have a phone and a tablet.

The passwords and usernames are very predictable so i can often use the next room's log in but this obviously doesn't work if the next room is occupied.

Is there any device (preferably small and cheap) that I can use to allow both devices to log in at the same time?

Does your tablet support Bluetooth Data protocols (Internet via Bluetooth)?

I just logged into my home WiFi Router with my i-mobile phone running android 4.3 and enabled Bluetooth and Bluetooth Tethering

With my laptop Ethernet and WiFi disabled, Bluetooth enabled, I was able to establish an 'Access Point' connection on the Laptop to the paired i-mobile phone.

I just composed this message and posted it using it. Seems to work fine. (Works like a WiFi extender, draining the poor i-mobile's battery but not too quickly.)

Cheers. I'll give that a go.