Hi,
If your business belongs in Canada and you are supplying IT services to UK businesses then this should be Outside The Scope Of VAT, meaning you would not be required to register for VAT in the UK.
The UK business customer would account for the VAT under the reverse charge procedure instead of your business needing to register for VAT in the UK.
Please see the guidance below:
Place of supply of services (VAT Notice 741A) - 5. Reverse charge
Thank you.