Not this year.
The aviation industry has said because there is no universal international rules on mask wearing to avoid stuff like 'you can sit on a plane without a mask until you reach the airspace over X country', they will simply enforce mask wearing for everyone for quite some considerable time.
NZ, Australia and many parts of the Far East are probably going to be off-limits for tourism this year at least.
The US is going to be difficult for unvaccinated children of all ages - they are allowed in, but my not be able to do things whilst there, with some states requiring all children over 5 to be double vaxxed to do anything like go to a restaurant or museum. Which given the uk are even planning on vaccinating under 12, is going to catch a lot of families out.
With Europe, i do think things will be easier, but our third country status complicates things. I think Germany, the Netherlands, Austria and Italy could be the ones that are strictest over the summer. I think France will ultimately relax sooner than them. Austria is making vaccinations mandatory for its citizens so they aren't going to be more relaxed for tourists.
I think the big thing will be day to day vaccine passports rather than entry requirements which will be the problem and thats going to be in force until next spring at least a few countries.
I think its also worth always being aware of what happens if you find you are covid positive whilst abroad or if you are identified as a close contact. You might still be required to isolate, which has other practical issues.
An unvaxxed 13 year old is going to be a bit of a nightmare tbh. Its going to be difficult to know what you will be able to do where.
I'm not booking anything abroad just yet and i have a 7 year old which is a lot less complicated. The extra costs and hassle of tests as well as the general uncertainty are putting me off. I think we will probably have a rethink in a couple of months, but for now nope.