My daughter who is now almost 8 also has a lymphangioma in the upper lip. She's had 2 surgeries and is getting ready for a 3rd next week. We live in the US. We are fortunate to have a great doctor who doesn't rush to have surgeries but allows us to make the decision of when with guidance and advise along the way. I have not regretted either surgeries as it helped tremendously with the ulcers which were very frequent and pretty bad in the first few years. She now only has them when she's a bit under the weather and they're barely noticeable.
Whatever you decided, know the choice is yours to make. Good luck.