"Heathrow express"... $87.00. I'm not sure what this is. I assume this is getting from the airport to our hotel or something. I dunno, I have to ask the agent.

The Heathrow Express runs from Heathrow airport to Paddington Station in central London. Tickets cost £13 each one-way. If your hotel is near a Tube (underground) station, then it's easiest to get there by Tube. Otherwise, you might as well get a taxi from Paddington.

You can alternatively get from Heathrow to the centre more cheaply on Tube alone, but it's a much longer, noisier journey (60 minutes not 15).

On the other hand, your other post says you fly in to Gatwick, London's other airport. Which is it? Plenty of trains run from Gatwick into London (to Victoria or King's Cross Thameslink stations), for about the same price. (Except, by the sound of things, between about 0130 and 0530). The "Gatwick Express" is non-stop to Victoria, but it's probably more expensive than normal train services and not a huge amount faster. Again, once at any main London railway station, getting to anywhere else in London is dead easy on the Tube.

"Britrail Days Out Pass 2 days within 8 days"... $209.00. I believe what the agent did is quoted some kind of a bulk pass on the rail system that we could use any time, rather than just a one-way point-to-point ticket to Cambridge. I think it's because she wasn't certain when exactly we were going to Cambridge.

Sounds that way. Considering that, by the time you get here, you will in fact know exactly what you're doing, it should be way cheaper to get the exact tickets, even if you buy them at the station on the day. Trains from London to Cambridge leave from King's Cross station, which once more you can get to from anywhere else by Tube.

"Eurail Selectpass 5 days within 2 months"... $760.00. I think this might be a similar thing to get us between Amersfoort and Germany, and within Germany for the week we'll be there.

I don't know anything about Europe rail travel. Rob?

Peter