Just use every chip as a 25p, it simplifies the game considerably.
Or nominate 1 colour as the £ chip, and all else are 25p"s
The last thing you need when playing your cash games, are 3 or different types of chip, or you may aswell just use coins of the realm. It will take just as long counting the chips as the coins/notes.Certainly as a lot of home players splash the pot and put a mixture in/and get it wrong also?
Simples 
Something like this ^^^^^^
If you play in a cash game in Vegas you will usually only see two denominations of chips on the table, if you exclude the odd chips that the dealers use for the rake - one or two of which sometimes find their way into play.
IE. In a $1/$2 game you see $1"s (white) and $5"s (red). They don"t need anything specific printed on them... how hard can it be to remember the denominations of two different colors?
In the OP you say you are looking for "25p £1 £5 and £25" chips... what game is going to need to have 25p and £25 chips in play?
If you want to play 25p/50p blinds, I would suggest making it a "1/2" game, use two colours of chips (1"s & 5"s) and have a 4:1 exchange rate when you buy-in/cash-out. If it"s a 50p/£1 game, use the same two colours of chips, with a 2:1 buy-in/cash-out ratio... obviously make sure all chips are accounted for if stakes are likely to change from one game to the next.
