Travel plan doable for a 20m old? ✈️

I want to plan a two or three week holiday which will mean flying from Germany to Scotland... DD will be 20 months old. I have no idea what she’ll be like when the time comes because she’s only 7 months old right now. But I could certainly do with a holiday (actually I’m British and I emigrated - I really miss home) and forward planning a year ahead is the only way we can afford it. It’s also necessary for my husband to book his holiday time well in advance at work.

Here’s the plan:

2 hours in the car (no stops?)

Airport time (check in etc.)

2 hours on plane

3 hours in the car (or longer with stops)

Arrival at destination

Doable with a 20 month old, or should we wait longer? Please post your travel tips and stories with babies/toddlers of this age, or thereabouts.

Thanks 🙏🏻