Buttons, he will be fine I'm sure, but as Sally said you need to start getting him used to short periods on his own and gradually build it up between now and the end of the holidays.
I'm over-sensitive to it, because I recently had to do some intensive behavioural work with Lurcherboy when he developed Separation Anxiety after Oldgirl died and started full-on howling whenever we left him. We started off with him howling after just 3 minutes, but he can be left an hour and a half without starting to whinge now. It was very hard work, really intensive and I pretty much had to put my life on hold and be trapped in the house other than school runs for almost 8 weeks. My neighbours were lovely about it, but I'm sure they won't be impressed if they get back off holiday and we have another howler in the house. The idea, based on research re his SA type and advice from knowledgeable sighthound owners, was that getting another dog would be company for Lurcherboy. I think I'll start howling myself if I just end up with double trouble!
Fortunately, we've had a bit of a breakthrough with it today. I dropped a few pieces of cooked chicken into his puppy kong, put it in his crate with him and he didn't even notice me leave the room. Kept him quiet for 10 minutes while I played ball with Lurcherboy in the garden, until he had a bigger piece stuck in the kong and got frustrated. So I chopped that up, put it back in and got another 5 minutes peace. Feeling less worried about it now, as I'm sure by September the little piggy will be happy to nosh down on a well stuffed kong or playing with a treat dispenser when I have to pop across to the school. I wasn't sure it would work, because Lurcherboy doesn't do kongs. He's such a lazy boy and will eat treats dropped out of a ball toy, but won't bother with a well stuff kong, because it's too much like hard work.
Pip's crate is massive, but I think - judging by how much he's grown in just a week with us - that he's going to need it. We currently have a divider in it and he's just using half, but I'm thinking I'll gradually move it back until he has room to play with a treat dispensing toy in there as well as a kong. He could easily run around in it currently, if we took the divider out.