They are wrong, or misleading you, their job is to protect your employer not you. Intermittent conditions of any type are specifically called out as being covered under the act, provided that the severity and duration of your condition meets the general impairment and long term definition criteria of disability. Y
This extract below is from the uk government's own written guidance on the law. You could also refer your OH to the Goverent response to the petition about it which confirmed this that women are covered if they meet the criteria. If they weren't then there would be indirect gender discrimination going on as arthritis, depression, meynieres diseasds are covered and are fluctuating conditions
If you want to stay in your job suggest you get a consult with a employment lawyer and ask them to write a solicitors letter to make you a written case clarifying this to them. That will then make it legally risky for your employer to fire you.
" Recurring or fluctuating effects
C5. The Act states that, if an impairment has had a substantial adverse
effect on a person’s ability to carry out normal day-to-day activities but that effect ceases, the substantial effect is treated as continuing if it is likely to recur. (In deciding whether a person has had a disability in the past, the question is whether a substantial adverse effect has in fact recurred.) Conditions with effects which recur only sporadically or for short periods can still qualify as impairments for the purposes of the Act, in respect of the meaning of ‘long-term’ (Sch1, Para 2(2), see also paragraphs C3 to C4 (meaning of likely).)
C6. For example, a person with rheumatoid arthritis may experience
substantial adverse effects for a few weeks after the first occurrence and then have a period of remission. See also example at paragraph
B11. If the substantial adverse effects are likely to recur, they are
to be treated as if they were continuing. If the effects are likely to recur beyond 12 months after the first occurrence, they are to be treated as long-term. Other impairments with effects which can recur beyond 12 months, or where effects can be sporadic, include Menières Disease and epilepsy as well as mental health conditions such as schizophrenia, bipolar affective disorder, and certain types of depression, though this is not an exhaustive list. Some impairments with recurring or fluctuating effects may be less obvious in their impact on the individual concerned than is the case with other impairments where the effects are more constant."
Page 29 on the first pdf document listed on this page
Link to the pdf itself
The general definition is here
Below is the equality act commissions guidance on dismissal and what employers must do and not do to avoid discrimination. Read the section on disability.
Fourth link down from this page if the above link does not work