This is true as there are only deals available on o2, virgin and
vodafone at present :-(

My recommendation would be to get a new contract as you can get this
phone completely free on a o2 200 contract over 12 months - which gives
you 200 Anytime minutes and 100 text per month free thus wiping out
PAYG charges etc. This is a cashback deal though so you have to pay the
£30 per month then claim the money back at set stages. This way you
can use the contract sim card in the phone OR put this in another phone
and use the phone on it's own. I am not sure if the 12 months free deal
phone comes unlocked but can find out if you are going to go down that
route of using a Orange PAYG sim in it etc?

You can see all the current UK CL75 Poppy deals compared on my site
here:
http://www.mobilechecker.com/compare_mobile_phone_prices.asp?hs=cl75

You can restrict the searches to PAYG only, SIM FREE etc but this phone
isn't available as sim free as far as I know...

Andy