Another popular reference is British Commonwealth Coins by Remick, James, Dowle & Finn if you can find one. 3rd edition was published in 1971.
I don't think you will find anything to cover the modern stuff apart from Krause due to the diarrhoeic output of modern commemoratives.
You are unlikely to find cheap useful reference books as the specialist volumes are usually out of print and were never produced in great numbers anyway. A few pounds if really fortunate, but frequently tens of pounds or even hundreds.