The plans here are not recent record breakers, although Bob's F1R and the Cargo Lifter Loafer are still record holders!
Many of the latest F1Ds are very similar to the Big Square in general proportions though most do rely on boron to strengthen the wing and tail spars.

Gyminnie Cricket Mike Colling plan here Kits are available from the BMFA.

F1R Entry level Tony Hebb plan here Build Instructions can be found here.

LPP Cezar Banks plan here

LRS John O'Donnell plan here

F1R International Bob Bailey plan here for Bob's ultimate CAT IV British Record Holder 36:50

F1L Grace 2 John Tipper Plan here and here for an F1L that would serve nicely as a first model in this class.

F1L Cargo Loafer Laurie Barr plan here

F1D Big Square Bernie Hunt plan here

F1D TGIF1D Tony Hebb plan here for this 2013 British CATIII Record holder at 34:08

F1D SM55 Slobodan Midic plan here for this classic 2010 W/Champs model, Serbian Cat III Record 35:22
weights and prop outline here

F1M You will find several plans on the INAV Index.

IHLG Mark Benns First is a CAT II model plan here.
The second is a CAT I flapper model plan here with templates here
and really useful build instructions.

CLG Merv Harris Low tech catapult glider that can get to the top at Brabazon. Plan here.

Legal Eagle plans and rules are available on the Clayton Green website here.

Many other plans, including Lutz Schramm's record holding F1D, are available online for every class of indoor model on the INAV website.

Other plans would be welcome.