Thanks for your question - I am Sam and I am one of the UK tax experts here on just Answer.
Yes you will have a capital gain tax arising in the UK - as since 06/04/2015 any properties sold with overseas landlords remain liable to tax in the UK - you should alert HMRC of the sale within 3 months - and then declare the gain made on the next self assessment tax return.
Whether the whole gain is liable here in the Uk or just the gain made from 06/04/2015 to the date of sale depends on
1) Your residency status since Dec 2012 (if you spent more than 90 days (or pro rata for the year of departure)
2) how long you plan to remin out of the Uk and have on residency (due to spending less than 90 days in the Uk each tax year)
I have added a link regarding the new rules here
Do let me know how I can assist further