Data and Voice SIM Cards, Pay As You Go
If the LBW Wifi system is insufficient for your needs you could consider buying a PAYG SIM.
Buying a £1 Vodafone, or EE, Pay As You Go Subscriber Information Module card and a £10 Top Up Voucher. At time of writing this gives 5GB of data which should easily last the event week.
PAYG SIMs are now easily bought at many supermarkets and many mobile phone shops to put into your unlocked smart device for the event week. Supermarket checkouts can sell you a Top Up paper voucher with multiple digit voucher number by cash or card. The voucher is valid for six months if not activated. Some bank Automated Teller Machines also sell you Top Up Vouchers.
So forward advise your family of your temporary mobile PAYG number before the event.