While it would seem safe to assume that the Pokémon TCG cards which were the focus of scalpers in the US earlier this year will be included, at this stage McDonald's has not yet confirmed the exact contents of these Happy Meals. The 2021 McDonald's Collection set of Pokémon Cards released in the US earlier this year featured 25 cards, reprinting all feature starter Pokémon from various Pokémon TCG expansions from the Black & White, XY, Sun & Moon, and Sword & Shield Series in both Non Holofoil and Confetti Holofoil versions. Each card retained its original layout, with the 25th Anniversary logo in the bottom right corner of the card's artwork. Assuming McDonald's UK and Ireland incorporate these cards into their own Happy Meal promotion, it's likely these will be distributed in much the same way they were with US Happy Meals, with each meal included one packet of four random cards, with one card per pack being a Confetti Holo. Rampant scalping of these cards in the US Promotion led to McDonald's being forced to issue a rare public statement responding to the shortages, and even having to offer customers "back-up" (presumably non-Pokémon related) toys where stocks had run out.
Given that McDonald’s UK and Ireland had previously pledged to remove plastic toys from Happy Meal offerings starting this year, it's possible that other toy items included in the US Happy Meals, such as the TCG card box and TCG display frame, may not be available in Happy Meals across the Atlantic. Several recent UK Happy Meal sets have substituted cardboard craft sets, including both the current Spongebob Squarepants line and the previous Jurassic World: Camp Cretaceous promotion, so it would seem a reasonable bet that similar cardboard playsets may be included for Pokémon.