I lost my phone but have been a long term customer with o2 for about 8 years now (pay and go).
I have already got a replacement SIM and phone but the phone is an old Sony Ericsson which was bought on Orange by my sister a few years ago.
I don't want to move to Orange because that means my girlfriend will probably switch aswell and then it will cost more to call my O2 friends plus I like my current tariff aswell.
Do they provide them or will they bascically tell me to pay some dodgy phone repair shop to unlock it for a fee?
They won't provide the NCK, as it's locked to another network. However, your girlfriend should be able to get the unlock code from Orange for around £15.00. Your other option is the one you mention.
be careful tho, about unlocking from the local repair shop. I have known phones not to accept internet or MMS settings if they are forced unlocked. Dont get me wrong, yours probably wont be a problem, just be aware of the risks.