Hi,
The Vodafone Pay As You Talk number that you were using would have been
recycled for non-use. If you dont make a chargeable call after three
months (or 90 days) the number falls into a semi-quarantine state. You
then have a further 90 days to top up the mobile and make a chargeable
before it falls into quarantine where the number is recycled for
another user and any calling credit lost.
You can pick up a free SIM card from Vodafone on their UK website at
the moment at the below link. Vodafone are currently offering a feature
called Free Weekends. If you spend Ł5 during the week then this will
give you free calls and texts over the weekend.
http://shop.vodafone.co.uk/Vodafone-SIM-Packs.htm
As long as the mobile has been unlocked then it should be possible to
use any SIM card you want with it. I take it if you were using a
Netherlands SIM while overseas that this is successfully unlocked / not
locked to begin with, so no problems there.
Any other questions then please let me know.