This mifi dongle takes a sim, and it acts as a wireless hotspot, and you can connect up to five devices at a time.
It is basically a router which sends out wifi from sim cards. It is locked but there are instructions online about unlocking it so you can use a sim of any network in it.
If you use this promotional code:
You get a £10 voucher which can be used at the online 3 accessories store.
Just cancel after the first month, i.e. give notification of cancellation the day you receive your package, and go with the £5.11 2gb1 month contract plan for data only