Royal mail

Perhaps best to have them sent to your hotel and use a trackable service like FedEx. Costly but dependable.

You might want to verify that the insurance available from whichever carrier you choose will pay off if the tickets do not arrive on time and you miss the game. Not that that is at all likely, but this came up when I mailed some tickets of my own 10-15 years ago. At that time the Postal Service's insurance would cover the tickets if they failed to arrive within XX days (might have been 30??), but not if they were simply delayed enough that they arrived after the ticketed event took place. For all I know, that policy may have changed, and FedEx/DHL/UPS might be different, but don't assume that is the case without researching the details. I believe all the carriers will refund the cost of express shipping if delivery doesn't occur within their advertised standards, but getting a refund of the shipping cost would not be adequate compensation if the tickets arrive too late to be used.

When not have them sent to your hotel when you buy them, and have the hotel hold them. More sense than sending them transatlantic only to send them back transatlantic.

Royal Mail first class usually delivers overnight, sometimes two days. Royal Mail second class usually delivers in two days, often overnight.

Royal Mail to the US is usually about 7 to 9 days, occasionally a couple of weeks or so. There isn't a slow service much anymore except for large packages, with takes as much as 12 weeks.

Much simpler just to have the hotel hold the letter.

The service you are after is Poste Restante:
https://www.postoffice.co.uk/mail/poste-restante

However, if you can, rearrange things so you pick up the tickets from the Wembley Stadium box office.

Have the tickets held at Wembley.

Did this when the Kaepernick led Niners ( my team) trounced the Jacksonville Jaguars in 2013.

Easy peasy.