Where abouts in the UK, Queenie?

I'd say that it would be fine to travel, at least at 5m pregnant people may give you a seat on the tube. I travelled at 3m pg and no-one gave me a seat! You may not even be showing too much at 18w, so you won't have to worry about comments on the way out, even at 26w you may still just be looking a bit on the larger side if you wear something a little baggy, so that should stop any and all comments.

The only thing with the hospitals is that as your pregnancy is a "pre-existing condition" you'll need private insurance to be able to get your scans and things whilst over here. But if you have a fall or any worries then you will be treated without any problems - in fact, getting money from overseas people is something the NHS doesn't really follow up with, that's why it's so broke!

Good luck with your studies and I hope the second trimester treats you well.