Here are the options possible for your stamps. I will give you the Scott (ST) and Stanley Gibbons (SG) numbers. You also need to check the watermark (see your catalog for details, but I put a description below in case you don't have access to a catalog), and determine the die on the first two stamps. They are either ST 162, 162a, or 190.
The third stamp is ST 442.
Watermark Simple Cypher - you will see a crown with GvR underneath in cursive. This only appears one time on the stamp.
Die I - ST 162, SG 366, 367, 368, 369 (depends on the shade of orange. 366 2d Orange-Yellow - Die I, 367 2d Reddish-Orange - Die I, 368 2d Orange - Die I, 369 2d Bright Orange - Die I).
Watermark Simple Cypher, Die II - ST 162a, SG 370.
Watermark Block Cypher - you will see a crown with multiple block letters GvR on the entire stamp.
Die II - ST 190, SG 421.
This exists with the watermark upright (SG 421) and sideways (SG 421b). There is also a non-watermarked (SG 421a) version of this stamp.
The third stamp is a new design, but is on paper watermarked Block Cypher. ST 213, SG 442, or if the watermark is sideways SG 442b.
You might consider finding an old Stanley Gibbons catalog if you collect British stamps. It will help you with identification. I see them on
ebay all the time. The new ones have current prices, but the old ones are still good for reference.