P45 time if you're in a situation to do so. It sounds like they're offering you your holiday when they know that you can't take it. Or they're taking advantage of your nice nature.
Many years back I started a new job and had a six month probation period. I worked unpaid overtime. At least an average of 1 hours a day just to get jobs complete and to put that extra effort in. Left early to travel 100 miles etc. Working out of my area that others wouldn't travel to. Always commented on, going well I thought. I liked the job and wanted to progress.
One week short of completing my probation I had the flu. I was paid this week as sick pay. Then a month later it was taken out of my pay leaving me short. My direct manager me informed me that it was management discretion and they had decided not to pay it. Which my contract did state, but I thought at first fair enough they've noted my hard work and decided to pay.
Fine I thought. No more overtime etc. I finished on time every day from then on and worked to my contract. When asked about unfinished jobs I'd quote the level of work and the time given and ended having to go back the next day and having my jobs shuffled around. In the long run they lost out. As I worked to the defined times per job that they had set and all jobs were always longer. Where previously I wouldn't take my lunch so that I could drive to another job and just eat whilst working. Now I would sit in my car for an hour and then it would be too late to start the job as by the time I took one hour lunch and arrived at the next site it would be too late to start.
Also when I asked for holiday during a busy period for a wedding. Much like yourself, but a few months in advance I was told no. Yet my manager who actually worked in the same job as me went on holiday for a week. Shortly afterwards I left. A company who takes and takes is not for me.
Others will no doubt say it's in my contract not to pay sickness in the first six months, but two things stick with me. It was one week short and I'd never been off, or late and had been noted for working hard. Them playing so tight to the rules made me do the same and soured the working relationship for both. Although they couldn't say anything. As I was working to my contract.
I was happy to be flexible, but if they can't why should I?
Sorry to drag on, but my point is that there are plenty of employers out there who are reasonable and look after their employees.
I've had other jobs since where I've worked during my holiday if something happened because they've been flexible with me when I needed a half day off, or needed to work from home etc. It needs to be a two way relationship for me. It doesn't sound like it is for you. You should go somewhere where they actually are flexible and not just for their own needs.