Looking To See If These UK Stamps Have Some Value

They can be very difficult to see.

Are these Penny Reds with letters in all four corners?

If they have letters in the bottom corners and 'stars' in the top corners, you will not find a plate number engraved on the stamp itself.

1841, Plate 23, note only letters in lower corners and imperforate: no plate number in design


1856, Plate 37, note only letters in lower corners and perforated: no plate numbers in design


1868, Plate 111, note letters in all four corners: plate number '111' appears in scrolling to left and right of portrait.

Watermarks?

I do not understand what your question "Watermarks?" means.

The watermarks are irrelevant. All 'Penny Red' stamps with letters in all four corners have the plate number engraved into the die. No one of those with letters only in the bottom corners have the plate number engraved into the die. The former exist only perforated, the latter exist perforated and imperforate.

As for OP's initial posts: OP posted British stamps issued during the reign of King George V. The permanent stamps come with designs that use a three-quarter face portrait and a profile head,

The former was based on photographs taken by the court photographers who had the family name 'Downey'. Consequently, the stamps are known as 'Downey Heads.'

The profile head was the work of Bertram Mackennal. These are known as 'Profile Heads' or 'Mackennals.' These exist printed using surface printing and using photogravure. The latter are easy to identify as the background to the portrait has a solid colour instead of lines.

For almost all other stamps, you have to check the watermarks to even get an idea of which stamp you may be looking at. The watermarks used during the reign are: