Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
If your UK house was your sole of main domestic residence then, although you are liable to Capital Gains tax (CGT) on any gain made on disposal, you are entitled to Private Residence Relief (PRR). PRR relieves CGT at 100%. PRR is given automatically and there is no requirement to declare the gain on your annual self assessment tax return if you make one.
I do hope that I have been able to set your mind at rest on this matter.
Not the slightest, the law on this matter is quite specific 'your sole or main domestic residence.' Note the word 'or' not 'and'. HMRC would love it to be 'and' and like to interpret it as 'and' in disputes, but it is not. You are disposing of your sole or main domestic residence so PRR applies. That you rent accommodation in Switzerland matters not one jot.
Thank you for your excellent support.