Hi YMD
Welcome to cR0... Manchester, mmm Rice and Three

Don't worry about the colour of the Fenugreek seeds, I've bought yellowish and brownish seeds in the past, two main points to watch out for:-
The seed powder is a strong bitter spice so use it sparingly, too much will ruin a curry and also give you gas and possibly the S**ts.
If a recipe calls for Methi make sure its not Kasoori Methi which is the aromatic dried leaf of the fenugreek plant.
Many authentic BIR/TA recipes call for Kasoori Methi, which is why its part of the chef's worktop (to hand) spices, here in the NorthEast,
it used to be added to the majority of savoury curry dishes. But not so much now in The Modern BIR's, because its overpowering.
Methi Seed/Powder however is a secondary spice with very limited use.
My two pennies, hope it helps

cheers Chewy