Check with the place where you made the seat reservations, SNCB I believe. It should be explained in the email you’ve received about the cancellation. They should provide those alternatives (or you ask for them) :

• TGV Lille-Flandres (easy 10 min walk from Lille-Europe) - Paris-Nord 19:12 - 20:14
• TGV Lille-Europe - Paris-Nord 20:51 - 22:08

I’d choose the first option. If they don’t answer to your call/email on time, these 2 TGVs are available for 10€ per person and have plenty of seats left. So you’ll get to Paris on Saturday, don’t worry

Hi thibcabe! 
Thx for your reply. No, they did not provide any alternatives in the email. Will ask. I am able to change the tickets through the SNCB app for an earlier train Lille Europe - Paris Nord at 5.51pm and tickets are available for my group, do u think that would work or it’s likely to get cancelled again due to strike (not sure how the strike works here). 

Am travelling with a big party of 8 including 3 kids, a lotta luggage, so would prefer not to walk to another station if possible. 

It shouldn't be a problem to choose the 5:51pm train if you're easily able to do that through the app (as long as SNCB doesn't charge you extra).

Saturday isn't a nationwide strike day so I don't really know why your train was cancelled... I do not expect the 5:51pm to be cancelled

Btw travelling between those 2 stations wouldn't have been a problem : it's mainly a short walk through a square. There are much worse places to transfer But I can understand that

I will ask sncf for alternative options before deciding. 
How can I get food at Lille Europe station if I need to wait for later trains - are there food shops at the station or cafe in the train itself? 

Yes there are shops and cafes in the station + there's a big Westfield shopping center around the corner.

There are restaurant carriages on trains but they often are quite expensive

There are dozens of restaurants, eateries and bars in the neighbourhood of the stations in Lille ( a bit More around Lille Flandres). The last thing you’ll risk there, is to be hungry :)

Thank you for replies on food, am travelling with 3 kids so always worry about their food .
 

I bought tickets from b-Europe.com website but received email from a sncf.com no-reply email (see pic). How are they related?
 

I can’t find customer support email for sncf. I submitted a complaint form on b-Europe site requesting for alternatives to the cancelled TGV 7242 hopefully they’re fast in their response. Is there another email for faster response? Is there anything else I can do? 
 

To contact SNCF : https://www.sncf.com/en/customer-service/contact-us/telephone

SNCF is the company operating the train and SNCB (Belgian Railways, b-europe.com) is the place where you bought the seats so you should contact them first but try with SNCF too.

All sorted. Contacted them on their fb page. SNCB says ok to change trains on app with no extra charges. SNCF says the TGV for 1751 is scheduled to run. 
 

thanks a lot, guys! 

Hope your journey goes well on one of the busiest days of the year ! :)

Arrive 45 min-1h in advance for the Eurostar for passport control and then enjoy your trip under the Channel

Thank you! I hope so too. It’s busy because of school holiday for London, right? 

Yes it's Spring bank holiday in the UK and Monday is a holiday (Whitsun) in multiple European countries such as Germany, Switzerland,... so a lot of people are travelling

I'm currently sitting in a crowded regional train (in Switzerland) that is usually pretty empty on a Saturday morning

Wow! Gonna be interesting train ride. Safe journey to you