Oh good, I'm glad it's not just us doing this! Due to move early next week, there was such a faff over exchange, plus the EA had been quite discouraging about it when we'd mooted it a month back, so it felt too awkward to ask for a visit to measure up now. Part of me also feels that because I would hate it if our buyers asked to view right now (with the state of the place due to packing - yes, they'd expect it to be messy, but we'd also feel an obligation, and a lot of wasted time, trying to make it vaguely presentable!) it would be hypocritical to do this to our sellers. I am so, so grateful our buyers haven't asked; I was expecting them to - and would not have blamed them - it IS a totally reasonable thing to want to do.
So like you, we reason - things will either fit or they won't, and everything will be a nice, fresh surprise! I think it helps we're moving to a place 60% bigger, so there will definitely be space for stuff, and we can re-arrange properly once we're in - otherwise I'd have been more concerned. We're bringing our bedroom curtains with us so they'll probably cover most windows as a temporary measure until we can hit up Dunelm or whatever. We've obtained a 4G router for Internet. Everything else can be sorted out with time 
Most of our four children haven't even seen the place... and we only saw it once ourselves back in Feb. Hopefully we'll still love it or we have a problem..!
To the OP - check the stairs; will beds/wardrobes etc easily fit up especially if there's a tight bend, or should you get them completely dismantled in advance? Also see if you can find out the location of the stopcock, fusebox, thermostat, broadband/TV/phone line sockets, and other utility-related things, especially if the seller is there to ask.