Having been over in Chicago (and GB) for the last two games, it's probably worth saying to Bears fans that you can probably save the cost of your air fare just on the savings you'll make on beers and eating out, and just about everything else - really can't get over how expensive stuff is over here now compared to the UK!!
Anyway, quite a few UK based fans on the forum, so please reach out for advice and/or recommendations if anyone chooses to make the trip. Lots of ways to keep a London trip costs down and make it far more enjoyable - from better neighbourhoods to look for hotels, to good places to eat and drink - and importantly avoiding the really awful tourist traps that many foreign tourists seem to get sucked into when coming to the UK.
Was at the Raiders game a few years back - really is a great stadium and experience, plus it felt more like a home game for the Bears than anything else, so hopefully, if it is as seems likely against the Jags, who now have a good UK fan base, then I think it'll be a great atmosphere.