The 'firsts' are always hard, and the first holiday is no different. Our brains are still processing the loss and at each circumstance realising what that means to us.
I go to Brixham in south Devon every year, has become like a bit of a tradition lol, (for a while we had easy access to a house which was cheap so we would do a few weekends) my dad would often come on hol with us as we all got on so well, my first time there after losing dad was hard. Everywhere I looked my brain seemed to realise something else about my loss. Now time has passed I can see something and think 'aww if dad was here' and have a smile, and sometimes a bit of sadness but the sadness not to the same degree (or as often) as the 'first' - there was also the happy memories
Sending a hug xx