To be pissed off?

[Macaroni46]

DP said he'd be over around 4pm today (we don't live together) but have been partners for over 4 years.
Last time I spoke to him he was still at his allotment and said he wasn't planning on setting off until at least 3.30. It's a good hour 40 mins to 2 hours journey.
It's now 3.30 and he's messaged to say he's just got back from the allotment, needs a shower then will head over.
I've told him not to bother. We were meant to be going to look for a TV when he got here but clearly that's not going to happen now.
Earlier in the week I mentioned I'd been invited for lunch. I asked him what time he was coming today so I knew whether to accept or not. He said mid afternoon. So I declined.
So basically I'm furious and fuming and kinda annoyed with myself for a) turning down the lunch invite and b) caring so much
He has form for being late so I should've known!

Yes, very annoying.
Your mistake was to work around him. I know, because I do this too. But instead of asking him what time he was coming and then turning an invite on the basis of his fairly vague "mid'afternoon," the better course of action would have been to have accepted the lunch invite, and then tell him not come until whatever time would be convenient for you.
TV shopping is something that could take a while, and it's a bank holiday, so possibly early closing. Do that on another day, like tomorrow, when he has stayed over and is already with you to start shopping nice and early.
I can tell you, with my own recently developed gift of hindsight, that "mid afternoon " means "I'm not actually sure and am not going to commit to an exact time just yet" allowing for flexibility with the allotment and an unexpectedly sunny day. It doesn't mean "around 3" which is what a normal person would assume.

Seems he likes me to be waiting for him ...

So make him wait for you from now on.