Buying number plate characters in bulk
The point of buying characters singly is that you hold what you use. A bulk order should reflect the registrations coming through your door, not an even split across the alphabet — an even split leaves you short of S and L and long of Z.
Start from the area codes you serve
The first letter of a registration's area code tells you the issuing region: S for Scotland, L for London, M for Manchester, B for Birmingham, Y for Yorkshire, C for Wales, W for the south west.
Whichever letter matches your patch will be your deepest line by a wide margin. Every letter's page lists its region.
Then the age identifiers
The two digits are the age identifier. Digits 1, 2, 5, 6 and 7 cover the identifier ranges on most vehicles currently needing replacement plates, so they move faster than 4, 8 or 9.
Characters to keep shallow
I is not used in modern registrations and Q appears only on Q-registered vehicles, so neither belongs in a routine bulk order.
J, T, U, X and Z never open an area code, so they arrive only through the random three letters and sell more slowly.
Topping up
Order singles in the quantities you need rather than fixed packs, and top up the lines that actually ran down.
Prices are per character and the same whether you order one or a hundred of a line, so there is no penalty for buying to demand.