I am a citizen of both UK and Canada, can I work in the UK for a Canadian company and pay Canadian taxes only?
For a very short time, yes. If your Canadian company sends you from Canada to the UK to do a job for them for 14 days, that's fine. At some you will need to pay taxes in the UK. I assume that tax will be subtracted from your Canadian taxes because there is likely some treaty to avoid double taxation.
If you have always been living in the UK, then you pay UK taxes only, no matter where the company is from. You should describe your circumstances a bit more. Remember that we can't read your mind over the internet.
Basically three cases depending on your circumstances: 1. You are clearly not a UK resident. 2. You are clearly a UK resident. 3. You are somewhere in between and it gets complicated.
Your nationality doesn't matter much, except UK nationality allows you to enter the UK and work there without a work visa for example that other Canadians would need.