Someone posted about this last week so I thought I would try it . The offer via Martin Lewis email ends tomorrow. It does work. I put it in my Huawei mifi at work and used my ipad , it was instant.the free 100mb credit lasts 30 days. Any credit you buy lasts 30 days BUT the free credit from watching ads does not expire so I thoughtbI would just have them running whilst I am cooking etc and build up credit for when we are away. You dont use your data when watching ads. Novelty might wear off but I do love a bargain. I started building up credit before the sim even arrived. £1 well spent.