Round trip same day tickets to Cambridge

Do you expect to take the faster service from Kings Cross; or the slightly slower Thameslink from London Bridge, The City or St Pancras; or the slower service from Liverpool Street?

Look for Off-Peak Return tickets. (Return means Round-Trip and return tickets are usually way cheaper than two singles).

I had been looking at Liverpool because it was cheaper. I care more about price than the extra 15 minutes.

We are staying at a Premier Inn County Hall near the London Eye so expect would have to take tube to either location.

the off-peak time ticket is what you need. just came back from london, i took the train from slough to Cambridge, one way cost is the same as return, off-peak, you can come back to the train station any time you want. train is pretty frequent, maybe about every 30-60 min at most. From slough to cambridge is about 20 pounds.

I had been looking at Liverpool because it was cheaper.

I hope you weren't. Liverpool to Cambridge would cost a lot more.
Liverpool is a city in North-West England. Liverpool Street is a station in London. Please use the correct full place names, if you put "Liverpool" into a rail website, you would get totally the wrong result.

Thanks to responses I have found the off peak return tickets from London Liverpool Street to Cambridge on Greater Angela train line. It appears that I would have to pick them up from a self service machine at the station. Would it be easier for us to just purchase them on the day we want to travel? Would there be a person? I have to admit I am having flashbacks to the machines in Rotterdam I could not figure out a few years ago. The advance tickets I have purchased have been delivered in a pdf file to my email address which I was hoping for here as well.

It appears that I would have to pick them up from a self service machine at the station. Would it be easier for us to just purchase them on the day we want to travel? Would there be a person?

Picking up tickets at the machine is easy. Pick any machine, put in the card you used to buy the tickets (this is for ID purposes only) and type the alphanumeric code you get when you buy. It spits out the tickets.

I bought the tickets and hopefully it will be smooth picking them up, as some of you suggest. But I realized if it is not, we can always take the next train, since we have off peak day return tickets.

Thanks for all the help!