My wife and I attended the game in 2009 and were in London for 5 days. We had great seats - Sec 121 row 25. The UKPatriots purchased a block of seats thru NFKUK, over 150. We participated in the UKPatriots events including an amazing Patriots fans only event on the Saturday night before the game at a sports bar, 400 Patriots fans in attendance, where even Mr Kraft made a brief appearance on his way to see the Queen. Also in attendance were Troy Brown, Gil and Gino, Patriots media (the PFW crew and Brian Lowe from Patriots Today) and more than a few of the Boston media folks.
This year my son and I are going. We already have our flights and hotel (Wembley Plaza). As a member of the UKPatriots (for at least the past 8 years) we will be sitting with them, again. If you are interested in more information go to
www.UKPatriots.com about tickets and their events, which are still in the planning stage but knowing the UKPatriots as I do, this year will be even better than 2009.
The Colchester Gladiators Football Club sponsors a tailgate event at the Green Man Pub down the street from Wembley Stadium on game day and the NFLUK has a tailgate and other events of their own.
Ryan91 posted a diagram of Wembley and 2009 earlier in this thread but the prices are in GBP not USD. If the prices remain the same, which they probably won't, inflation you know and it is the NFL, and with a current conversion rate of 1.58, the ticket prices are not that inexpensive. In 2009 the conversion was 1.6+/- so I paid $160 for each seat. Current airfares run about $1,000 and if you plan on going but haven't reserved a hotel room, better do so now if you want to be anywhere near Wembley Stadium.
FWIW, London is a great place to spend a few days sightseeing and meeting the people. My wife and I are going back in a year or two to spend a week to visit London and also visit friends who live in Manchester.
Is the trip a bit on the expensive side? Yes it is but that depends partially on the conversion rate of GBP to USD. But it is well worth the time and the $$.