I'll try provide the knowledge to answer this yourself rather than just answer directly. So wall of text incoming. 😛
You can always just pick the top option if you don't want to get too hung up in these fractional variations.
With a lot of coins from this era, there are often several tiny tiny variances between coins. Numista typically issues a “generic” example at the top with known variations below.
It's caused by different dies being used in production. If they're not perfect matches, then the coins they produce aren't either.
Incuse means the design is cut in whereas raised is the exact opposite. If you imagine the field of a coin as being flat and you then run your finger along it. If there's a “trench”, that's incuse. If there's a “hill”, that's raised.
A “flan” is the blank piece of shaped metal used to make a coin. Planchet is the more common word these days, but flan is often used historically. So from the coin page, under the general details section, you'll see the thickness of the coin is supposed to be 1.6mm. So an extra thick flan would be anything bigger than that, for example if it was 2mm thick.
Proof coins are ones made for collectors, testing, dignitary gifts, or other non circulating purposes. With ones this old, assume yours is a circulating one unless you have it otherwise proven. E.g. This coin was gifted to the Wizard of Oz on his state visit to Queen Victoria & I can document it's history right to the moment it came into my possession.
“Leaves” refers to the amount of leaves on Victoria's wreath. Different dies have different amounts of leaves. Note how it mentions the lack of signature on the obverse; this implies the signature is visible on the reverse.
The notes about LCW are the engraver. In some examples, his name or initials appear at varying points on the coin. I'm sure that's fairly self explanatory from that point.
You may see “obverse” and “reverse” used, sometimes abbreviated to obv & rev. Obverse means front, reverse means back. Within the confines of the UK, the Monarch's portrait is always the front “obverse”. So on your coin, Britannia is on the reverse.
I think that covers what everything actually is. So let's actually look at your coin!
Quality suggests it was circulation quality so not any of the proof variations. And I can't pick out any signatures on either side so we can discount all of those.
I can't measure the thickness of the flan or feel the lines on the shield. To my eye, they look raised (i.e. you'd feel a raised bump on those lines).
Assuming those lines on the shield are raised and its normal thickness, I'd file it under “Raised lines on shield” - the 11% version.
P.s. As I said, if you really don't want to get lost in the rabbit hole of miniscule variations, or its impossible to decifer (e.g. too worn to tell), use the top “generic” option - the 4% option.
I hope that helps & have fun with your coin hunt.
