Thanks all for the responses.
What has been said was what I expected however I have come across the following in the Package T&Cs so will phone up and ask as you never know.
Originally Posted by Package booking terms and conditions
7.4. Amendments to your booking
7.4.1. If you wish to amend any part of your booking after your contract with us has come into existence (for example, transferring to a different hotel, amending to multiple hotels, asking for a different departure date, adding extra people or transferring the booking to another person) you should contact us and we will tell you if we can meet your requests. All amendments are subject to availability.