London to Brussels to Ghent

Yes, London to Brussels by train is about two hours. The time will look longer because there is an hour time zone difference between the two cities. The Eurostar train from London departs from St Pancras station and arrives at Brussels Midi station, from where there are frequent trains to Ghent.

Eurostar trains have airline style yield-managed pricing, so to get cheap fares you need to book around six months in advance on www.eurostar.com. If you book a ticket there from London to "any Belgian station", you can connect to any Belgian train you want within 24 hours of arriving in Brussels. The cheap Eurostar fares are strictly limited to a specific train and if you miss that you will have to buy a new full-price ticket. Note that Eurostar has airline-style security at St Pancras and you need to arrive at least 30 minutes and preferably 1 hour before your train departs. At Brussels Midi you can get on any train you want to Ghent.

Ann, Yes, the Eurostar train from London St Pancras runs to Brussels Midi. It takes ~2 hours. Timetable here: http://www.eurostar.com/sites/default/files/pdf/timetable/UK_timetable.pdf
You can get a train from the same station to Ghent. You can buy a ticket to "any station in Belgium", then you can just get the next train to Ghent, they run many times per hour.
You buy a ticket in advance (cheaper the earlier you buy) from the Eurostar website. The ticket will be for a specific Eurostar train, but any train from Brussels Midi to Ghent.
Lots more info here: http://seat61.com/Belgium.htm#Other%20destinations%20in%20Belgium

Eurostar ticketing operates like an airline. Advance purchase is dramatically cheaper, railpasses are no good, seats are reserved, and tickets cost more if they can be changed from a specific train. Immigration formalities are involved, even before negotiation of Brexit.

Any Belgian Station is a ticketing option, that costs more than just London-Brussels. Trains from Brussels to other Belgian locations are virtually all non-reserved, and can be crowded. They can also be local commuter trains, with narrow double-decker cars and no luggage racks at the entrances to the carriages.

All that said, it's a very nice way to travel.

Edit: You probably don't have time to stop over, but the train stops, once, in Lille, France. I went there for the art museum, but it's a long way from anywhere, except on the Eurostar. Don't know if they sell a stopover option. In fact, I had an eight-hour delay returning from London because of a pedestrian or truck accident on the tracks in France. Luckily, they held the last train to Antwerp from Brussels, Midi

Note that the Eurostar stop in Brussels is Zuid/Midi, a less well-known of the three, identically priced stops in Brussels. it's NOT as close to Grand Place as is Gare Centrale.

Edit 2: language correction for Zuid

Thank you both, this is excellent information and much appreciated. Kind of scary doing this by yourself when you don't know what you are doing!! Again thank you for all the information!

I just spent a few minutes on the eurostar website. Choosing the UK as "my" country, I could see trains through April, lowest price was £45. The "any Belgian station" option was £6 more. Using France as my country, there were trains through the end of June (London-Brussels), at €60.

The French site was easier to navigate than the British site.

In Gent you need to get off at Gent-Sint Pieters, not Gent-Dampoort.
Brussels being bilingual, the signs at the station will be alternatingly »Bruxelles Midi« and »Brussel Zuid«.

ton, I'm pretty sure I've gotten off at both Gent stations, depending on my train. And the "old town" is closer to Dampoort on foot than it is from St. Pieters. But it is certainly good to remind readers that selection of a certain station can eliminate many trains from your online search of any Rail company site.

The OP didn't name the hotel, so we don't really know the immediate destination.

I want to thank everyone for all your help! This is great, I don't feel so alone doing this! I don't have the hotel yet, but will soon.
Happy Holidays to everyone and to a good new year!

Ann, I stayed at the Ibis next to the cathedral (there's more than one Ibis). It was a great location, budget prices and while it lacks any atmosphere, it is clean and comfortable (especially the double bed). Either take a room with a view (over the tram line that runs till midnight and starts again around 5 am) or a quiet room without a view.

I'm pretty sure I've gotten off at both Gent stations
That's true, but as the main station Sint Pieters has better facilities.