I had only just pre-ordered from Samsung with the 10% discount when I received a 20% off code through the post.
This worked out cheaper for me over all and you can still claim for the free gifts through the Samsung website.
Obviously here you can't trade in. I have an S9 that would get me £200 from Samsung.com
or £135 from fonebank.com/
(best price I could find). I bought an S21 Ultra 512GB for £1063.20 and with selling the S9 will come to £928.20.
If you do have an eligible code from very.co.uk
it works out cheaper. I bought my S7 Edge from them before and it all went smoothly. The code actually works on many things site wide so ended up buying lots of essentials as well from them (like baby car seat, which was the last thing I thought I'd be buying today).
From Samsung, including the trade in, I got to £1016.10.
Both sites come with the free gifts if ordered before 28th Jan.