Hi hayley.lundall,
I thought I can answer for some of your questions regarding the OD for Qatar airways as I've read every single posts who wrote in this forum.
1. Can anyone attend the Open Day (My friend has a CAA Lisense and would like to apply? Yes! anyone can attend the open day without even an invitation, as it is open to everyone.
2. What to wear? If you want to give them a good impression, it would be a good idea to dress smartly. However, it's not obligatory at the OD. They'll tell you if you get selected, which will be the next day, to wear a formal suit with a skirt.
3. Are you allowed to wear colour contact lenses if they are tested or should I just wear my clear/natural ones?
At the OD, they don't even care whether you wear colour contact lenses or not. You've got only max 1mins to show off your good qualities to either of 2 recruiters.
4. Are you allowed to have a french Manicure a short length or should i just keep my nails short?
At the OD, they don't even care whether you have a french manicure or a short nails. (I feel like I'm repeating myself

)
As long as your nails are neat and clean, you won't have issues.
5.Is it fine if your photos are taken at home and printed and not in a professional studio. how strict are they?
At the OD, it doesn't matter. Again, if you get through the final interview, they will anyway ask for your photo taken professionally if you have them taken at home.
6.Any other tips for me?
I don't think I'm the right person to give you any tips here

, as I faild.
But most members here say 'be yourself and you'll be fine'
I don't get this. Maybe I wasn't being myself. I tried to smile all the time and they may have seen my unnatural smile(!)

It was just painful experience for me.
Anyway, wish you the best of luck
Hope it helped.
d-