If i ring a uk o2 number , from my o2 mobile and the person is in Poland on holiday will the ringing tone sound i hear be the same as a uk one or be different?

Yes, it won't be any different.

Always been different if the phone is abroad, in my experience.

aahh, so what is it? i thought it would be different as it would be roaming on the network in that country.

I find its not different if your still calling a UK number. Calling an international number, its normally different.

But when you're abroad the call basically gets forwarded to the host network over there - you get their ring.

This.. If the call is handed off to the network abroad you'll get the foreign network's ring tone.

Unless you're on Orange and calling an Orange number abroad - I've noticed then you get the UK "ring ring" - but with the usual Orange "longer first ring". This is because they keep everything on the home network until the "answer" signal is sent by the foreign network. This enables costs to be saved in case the call diverts to voicemail (ie: saves the bounce out there and back to the mailbox incurring costs to the user and the network). This tends to work only on networks overseas that utilize the CAMEL real-time technology.