Are you from UK?
If you are, T-mobile has a good pay as you go deal which offers a 1 day, 7 day or 30 day pay as you go without any contact. You can switch between the alternate day plans as you please. While the prices are not a good compared to other networks, the freedom you are given especially when you are not tied in to a contract with the other networks, makes T-mobile an appealing choice.
I've never used wifi hotsposts as there is none in my area but if you are only looking for occasional use of the supplier broadband, it costs Â£2 a day. You only pay for the days you access the supplier broadband so you don't pay for the days you don't use it on. If you were planning to use it for longer, you would send a text to T-mobile saying for either 7 or 30 day use, after that you would send another text specifying length of use.