Ok usual times if you have the £££ holiday care is relatively easy unless your DC is at school and not yet 5 in which case it's a bloody nightmare. Difficult weeks are between Christmas and New Year and possibly Easter week.
After primary is a bit tougher as general "holiday clubs" are less of a thing but cynically I'd tend to try to get DC engaged in specific interests where a holiday training camp would be an opportunity rather than childcare.
PGL always offered activity holidays, so do other more specific providers, local private schools.
The coming holiday I could book DC into a multi sport camp 25 minutes drive away covering school hours no problem. I also could sort 5 mornings at her usual tennis lesson provider which is on the way to DH's work.
I suspect that in non Covid times my usual wrap around provider would offer holiday club as well realistically leaving me with Christmas as the only impossible week.
Long term when DC is old enough I'd probably assume 1 residential week without parents, at least a week of family holiday, a week with grandparents and possibly a reciprocated week with cousins. Leaving some weeks of generic holiday club and other local interest activities.
Will cost £££ but worth it for my career.
Potential limitations are wrap around (similar to school day limitations) but many providers offer wrap around.
The only thing that looked impossible was DC1s reception year as being an August born she was 4 (therefore limited to 3 hour sessions by most providers) for most of the year but not at a nursery so at the back of the queue for a place.