one of the unlimited 4g sims, giffgaff
https://www.giffgaff.com/orders/unli...E&gclsrc=aw.ds
for 20 quid you will get unlimited 4g
or 3 HomeFi, which will act like your broadband router, only 40 gig a month though
http://www.three.co.uk/Discover/Devi...0&colour=Black
both can be on a 1 month contract