@Ncncncncc my sincere apologies. I think I read down the thread, got distracted by kids/dogs and stepped away - and when I came back and composed my comment it was in reply to another post.
To correct my reply - I would bloody well hope no-one would make a judgement about your thinness - if you’ve not declared your anorexia in the application it is none of their business, as there could be any number of reasons for why you are slimmer than most.
As others have stated, if it becomes an issue when/if you offered a job, you are protected by the disabilities act and can ask for reasonable accommodations.
The question is really, do you feel ready to go back to work, and to work full time? You may find it is really good for you to get out, meet new people, be distracted, but you need to feel you are in the right place and supported. There is usually a probationary period, so if you get offered a role, I’d suggest giving it a try and taking it day by day.
FYI there is an organisation that supports people with MH issues returning to work, the Richmond Fellowship, who were great with my DD. They are great at holding your hand through CV prep, application process and counselling about the types of jobs you would find easier to manage. I’d recommend contacting them at https://www.richmondfellowship.org.uk/