Playstation Plus Extra £58.99 / Premium £80.39 (Selected Accounts Via Console)

Gift cards via Currys seem to be cheapest at mo
use code PS15 at checkout to get 15% off all gift cards

£100 GC for £85
£90 GC for £76.50
£84 GC for £71.40
£80 GC for £68
£50 GC for £42.50

If you want PS Extra for £51 (49% off) Instead of this offer for £58.99 (41%off) or PS‌ Premium for £61.90 (48.41% off) Instead of this offer for £80.39 (33%off)
Look below

If you can see the current offers (premium for £80.39 or extra for £58.99) when signed in on your app or console this should work for you, also if you want premium dont buy it straight away...

Buy PS Extra 1st for £51 using currys 15% off giftcard offer
I got £60 gift card (2x £30 cards*) which will make your ps extra 49% off instead of 41%
*if buying more than one card make sure you buy them separately because discount only applies to 1 card and also try topcashback

Once your signed up go back into your app or console and you should now see an option to upgrade to premium for £13.40
Use your £1.01 change from the last gift card and buy another £10 giftcard from currys for £8.50 using 15% off giftcard offer and pay the rest of the balance £2.39 that's due by card

you effectively now get PS Premium for £61.90 (48.41% off instead of 33% )

both almost half price, hope that makes sense