UK Tax Questions? Ask a UK Tax Advisor for answers ASAP
Let me take a loom at that and I'll get back to you in a short while.
You might refer to RDR3 on the Statutory Residence Test here for the detailed rules on UK tax residency which came into force on 6 April 2013. A brief summary of the rules can be found here.
Assuming you are already treated as non-UK resident (did you complete a P85?), you need to work out the number of ties you have to the UK and that will tell you how many days you can spend in the UK from the links above in a full tax year. Most non-UK resident individuals look to spend less than 91 days in the UK in a full tax year.
I hope this helps but let me know if you have any further questions.