Quick UK property capital gains tax question

Hello,

I've a feeling that to someone familiar with the relevant laws the following question would only a few minutes to calculate the answer but as one hour is the minimum time, I've put a lower per hour budget than I would do normally.

I'd like to know what capital gains tax would be due in the following circumstances (once I've awarded the job I'll obviously reveal the actual figures):

1) I bought a property in Dec 2005 for X which I lived in with my now wife - we got married in Feb 2009, but the property remained in my name.

2) In July 2010 we moved to a rented property and let out the flat that I own.

3) As the flat had increased in value over this time, in June 2012 we were able to remortgage it based on a valuation of Y and put the extra funds towards a deposit to purchase another property which we now live in. When we did the remortgage the flat was transferred into both of our names.

I'd like to know what capital gains tax (if any) would be due if we sold the original flat (which we are still letting out). We are not going to move back into the flat at any point. If there is capital gains tax due please let me know if the amount changes based on when we sell it.

Thanks,