UK resident working in China

[Airbus123]

Hello

I would appreciate any comments on the following as I am looking to go contracting in china.

1. Mortgaged in the UK and reside with my family
2. Looking to contract in china 4 weeks on/off with off time back in uk.
3. Company contracting me will pay all liable chinese tax and my wage paid net.
4. How much would I be liable for in the uk? I have been made aware of the double tax agreement the uk has with many countries which include china.
5. If I contracted as a ltd company would I have any other liabilities to cover.

Apologies for any naivety as this is the first time I am looking at contracting work having been PAYE living and working in the uk.

Thanks