No worries....this will give times etc.

http://www.nationalrail.co.uk/

Make sure you enter the station as "West Hampstead Thameslink"

Wonderful link, ali, thanks! I'm sure that will come in handy when we're exploring England too.

That's certainly within about 5-10 minutes' walk of both West Hampstead stations:
http://tinyurl.com/ya4vz5k

Be aware that, from Gatwick, changing, whether at London Bridge to the Jubilee Line, or at Clapham Junction, is going to involve a bit of a hike with your luggage: and trains from Clapham Junction to West Hampstead are only every 20 minutes or so during the week (as flanner says, weekend service minimal).

I don't know the interchange at St Pancras, but trust flanner on that. Alternatively, and if it's the weekend, take a taxi from St Pancras. Those would be easier, it seems to me.

Thanks, Patrick. I like that map. I didn't realize there were two WH stations but I can see them on your map along with the ThamesLink. Our flat owner did say that it was just about a 10-minute walk to the station so it's nice to have that confirmed. I'm just beginning to shop around for airfares so much will depend on what time of day we land.

Thanks again, everyone.