Superb breakdown from @maxelly
I've used Unicorn Trails and Equestrian Escapes and the are both extremely helpful at sorting out holidays to match the type of riding you want to do.
As @maxelly says, always be honest about your level of experience and if in doubt, underplay. If you like the idea of galloping in open spaces but are more likely to be hanging on for dear life and not enjoying it - say so. Because they always have to match the pace to the least experienced/confident rider and that can be frustrating for people who were expecting to have a good hooley about.
I ride 3/4 times a week and the longest non stop holiday riding I've done is 5 days of 6/7 hour riding a day and by day 4 I needed ibuprofen to get on and by day 5 I was feeling it
I did a hilarious riding holiday years ago when I was much fitter where the day's pace was dictated entirely by what time the guy leading us needed to get back to his girlfriend/how much wine we'd consumed at lunch.
It was mostly sedate in the morning and breakneck in the afternoon!
I normally do ones where you stay - because DD is normally with me and sigh can't live without WiFi. Also Shen doesn't ride as much as me I don't want to to over face her by her having to ride to get to the next place. She'd probably love it and it would be me flaking!
Accommodation can be a bit basic - but you can upgrade.
I've got my eye on a Irish one where you "loan" horses for the week and ride point to point ok your own. That'll be me an my very horsey friend though. DD would be last seen galloping across an Irish beach will me trailing in her wake.
And Andalusia - to trail ride and do some dressage on Andalusians. Swoon.