voophroo

Hi, I live in UK for last 20 years.
Many years ago I helped financially my father who lives in EU by repaying his debts abroad (£10k.) Few years ago he gifted me a land as a "thank you" for repaying his debts.
I now want to sell this land and expect to get something in region of £13k.
I plan to give my father some of this amount (£3k-£5k) and keep the rest.
Do I pay tax in UK if I sell this property and how to calculate a capital gain?
In this situation, it's not a gain actually.
How to approach this situation?
Please explain what is the best way to approach tax implications that may arise.
Thank you!