Recommended resources for Higher Level Maths?

ExamLearn

Crazam

Dublin Academy of Education

Studyclix

Khan Academy (not Leaving Cert-based but similar content)

OpenStax (free textbooks on high school and college level mathematics (note that early year undergrad courses can sometimes be of a similar level to Leaving Cert))

It costs money, but the more expensive Studyclix membership offers past mock papers in each subject, if that would be of use to you.

Try the old school exam papers from Edco, Educate.ie etc. They may have some of their very own papers in among the official past papers.

If you are in school (or if you still have any contact with them), ask your teacher if they could get a hold of any old mock papers for you.

Not sure if I can give a definitive recommendation. I'm familiar with both Active Maths and Text and Tests. Both are divided up into two textbooks and have plenty of exercises. The Active Maths books are divided up between traditional Paper 1 content and traditional Paper 2 content. Text and Tests is a little bit more mixed up as I think they are trying to present it in a more 'natural'/sequential way where topics build on each other, without getting too repetitive, although I'm not sure if I would necessarily agree with their order (calculus before functions is unusual in my opinion). Regardless, you should start with the algebra chapters first, and then you can then (for the most part) move on to anything else. I think Active Maths' chapter layout is probably a little bit easier to follow as there is no real issue in following the books sequentially if you wish. Text and Tests might have a slight edge in terms of worked examples. I think that Active Maths can sometimes shy away from giving examples relating to the hardest of questions, sort of encouraging you to figure them out yourself, which can be a good thing in terms of discovery learning, but that doesn't suit everyone, especially if the goal is just to do well in the Leaving Cert exam.