I think I can help you here OP, if you haven't already done something to it. As others have said, do not colour and perm in the same week.
I'm a retired hairdresser and you are correct in that the chemicals in swimming pools can give a slight green tinge, however this is only glaringly obvious if you have a full head of bleached hair like we all did in the 80's-think Paula Yates - and the peroxide strength we used to get hair to go white was SO strong. The reason many people's hair went orange was because the peroxide used in shop sold box dyes,was not strong enough to lift dark hair to blonde so it stalled at the breast orange shade. Shop bought box dyes were not allowed to contain 60% strength peroxide. which was the only strength that could lift dark hair to really light blonde/the white that everyone wanted back then it It could only be bought in a hairdresser supply shop. It also knackered your hair condition but as we mainly had short hair then, it was ok if you used a really good conditioner afterwards.
So, I'd say in you first photo you have hair similar colour to mine - not so much the ones where you have cut it. I do home highlights (very subtle and not many). I have some white patches but mainly underneath and some grey but not a huge amount. I usually do two highlights near the front of my hair and four or five elsewhere.
I use bleach as it's the only thing that lifts my hair to the tone I want - but now use 3% peroxide with a good bleach.
If you want to try, (I'd recommend doing ONE) highlight only at first-this is not advice for a full head colour - full head colour is extremely dated and ageing and the root maintenance is horrendous.
You'll need:-
https://amzn.eu/d/7vgsZeg
https://amzn.eu/d/1Gt284u
https://amzn.eu/d/9yQOVMP
https://amzn.eu/d/gdsrhto
Mix the bleach powder with the peroxide until it's a soft paste. Needs to be soft enough to 'wet/soak into the hair - but not so wet it drips or so dry it wont absorb). DO NOT BE ALARMED THAT THE BLEACH POWDER IS BLUE - this is totally normal.
Take a THIN slice of your hair (clip the rest out of the way), and paint it onto one of the silver foils. Fold the hair up into the foil. Bit fiddly but not impossible. Leave it to develop for around 45 minutes. Take foil off and have a look. 45 mins should lift it to a nice subtle dark blonde. Rinse off with shampoo, condition if you want and dry). You won't see true colour until it is dry.
If you like it, do a few more. Don't overdo it and maybe get someone to help you do a couple on your crown.
BE CAREFUL AT THE ROOT THAT THE BLEACH DOESN'T LEAK or you will get a BLOB of colour which you definitely don't want. It's just like painting, and needs to be done carefully. - I leave a little root in any event as I prefer it like that.
If you get any brassiness, you can use purple shampoo and conditioner to take the brassiness out. If your hair is really dry. Use a hair mask (intense conditioner). DONT USE THR PURPLE PRODUCTS IF UKU ARE GOING IN THE POOL / THE SUN HAS BLEACHED YOUR HAIR. They cling on because your hair is porous and you could go very purple but it does fade away eventually. Use them about 3 weeks to a month after you are back if necessary.
This peroxide is the least damaging of of the peroxide strengths. If you want lighter, go up to 6%.
Lastly, to straighten, I use this products and I think it is fantastic and such good value for money
https://amzn.eu/d/gLu7SoU
I'll attach a pic of my hair - i just cut it straight round on the bottom - good sharp scissors are vital - Jaguar do reasonably priced ones - and there's a useful little gadget on Temu what helps you cut your hair in a straight line!
Good luck and have an amazing holiday! Sorry the better photo hasn't posted - I'll try on a new post.@