Yes, you can be dismissed on the grounds of lack of capability, for example poor performance, as it is one of the five statutory fair reasons for dismissal.
In the case of performance, dismissal should be the final step and taken only if, after warnings, your performance has not improved.
Your employer should have made the required standards of performance known to you, offered you training, if appropriate, and provided you with sufficient opportunity to improve.
Employers should not apply unreasonable standards. Company standards should be achievable by the majority of employees doing the job. Where the employee is disabled, employers also need to have considered what reasonable adjustments could be made and have taken steps to avoid needing to make a dismissal.
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