I'm quite happy with the package I have with o2 at the moment and don't want to change it, but I need a new phone so I've decided to buy one. Can I just buy a pay and go phone and put my SIM in it.

That should be fine yes.

Only caveats:

a) If you buy a pay as you go phone intended for another network, it'll almost certainly be locked to that network. That means your O2 SIM won't work in it.

b) If your current O2 SIM is quite old, it won't support 3G services. If you put it into a 3G phone then you won't be able to use the 3G services it offers and you might experience issues in general. O2 can supply you with a new SIM if this is the case.

Thanks very much. O2 don't offer the deal I have now so I'll get an O2 phone and try my luck. Thanks again.