I don't work Mondays. Will I miss out on bank holidays?

You should not miss out on bank holidays. 
 
It is against the law to treat part-time workers less favourably than their full-time co-workers unless this can be objectively justified. This means that you are entitled to the equivalent number of days holiday (including bank holidays) in proportion to the hours you work as your full-time colleagues. 
 
Because of this, many employers give part-time employees a pro-rated bank holiday entitlement, irrespective of the days they work. For example, if full time workers work five days a week and are entitled to the statutory minimum 5.6 weeks’ holiday per year, including bank holidays, and you work a four-day week, you will be entitled to 22.4 days’ holiday a year. This can be taken at any time as agreed with your employer. The same principle applies if your employer provides more holiday that the statutory minimum, so you get your share of any additional contractual holiday. 

As with all workers, you are not necessarily entitled to take the time off on a bank holiday, but if full time workers get bank holidays off and you are required to work it because you are part time, this would be less favourable treatment and you would be entitled to bring a claim under the Part-time Workers (Prevention of Less Favourable Treatment) Regulations 2000. 

As this issue affects all part-time workers where you work, this is an obvious case on which to take a collective approach if your employer is not treating its part-time workers fairly. This would be a good opportunity to encourage your colleagues to join a trade union to help you get organised. 
 
If you are not yet a member of a trade union, browse our Union Finder tool to find the union most suited to your needs.