It is legit that you need to sign the prize warrants.
They did announce withdrawal of paper cheque payments of prizes some years ago but were persuaded to defer doing so and as far as I am aware this change is still in the distant long grass.

Like most folks I have mine paid direct into the bank, but like to go on to the NS&I 'have I won' page onthe second working day of each month to check mine, Mrs HGB's etc.   (We have the same value of bonds exactly and over almost every year she wins something like thirty percent more than I do.  Reckon Ernie must fancy her)

They lowered the prize pot this month and are apparently going to do so again in January.  Sheesh.

Air fried salmon for us both with jacket potatoes for himself and stir fried noodles & veg for me with maybe some sweet chilli sauce stirred in for good measure

Chicken thighs are in the slow cooker will decide later if Im going to add spices and rice make a chicken dinner with mash and chunky mixed veg.

Toad in the hole, mash, thick onion gravy,peas,carrots & cauliflower

Meatballs, mash and veg.