Claim an unfair dismissal

Hi there, I would like to appeal an unfair dismissal as this has been due to discriminatory reasons. I have dismissed for leaving the office to see a doctor after having done 4h of work. The day after, my GP gave me sick certificate confirming I wasn’t fit for work. The day I left to see a doctor, I communicated to my manager by email and this has been the reason given for being dismissed as on the handbook says it can only be communicated on the phone or in person. All my colleagues request sick days by email and there is no issue. Previously I had requested I sick day by email and this has been accepted. The day before my sick leave ended, I sent an email to HR communicating I was going to come back to work. They replied inviting me to a disciplinary meeting. In this meeting, I was told I was dismissed for leaving the office to see a doctor and not communicating following the procedure stated on the company’s handbook. They don’t follow the guidelines on the handbook as everyone uses their email to ask for a sick leave. Therefore this can’t be a valid reason for a dismissal. Custom makes the law, and in this case, communicating by email is generally accepted but not for me. I'd like to appeal the dismissal and threaten them to take them to a tribunal as I believe this has been discriminatory dismissal for two reasons: - I am treated differently than my colleagues. -Nationality as the only 2 people dismissed since the company has opened were from the same nationality. In both cases, the dismissal has been not supported by any proven reason and there are no records on the HR file of any wrongdoing and a right process to claim a fair dismissal. I haven’t been in the company for more than two years but in this case, this is a case of discriminatory dismissal that can be appealed. I’d like an employment lawyer to take the case and draft an email to appeal the dismissal please. Kindest regards,